Japanese Kei Bases

Glossary:

削除する - to erase
変える - to change

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The Five Modern Japanese Kei Bases:

未然形 - (Kana: み ぜん けい) - passives, potentials, and negatives
連用形 - (Kana: れん よう けい) - conjunctions and desires
連体形 - (Kana: れん たい けい) - plain dictionary form
已然形 - (Kana: い ぜん けい) - hypothetical situations
命令形 - (Kana: めい れい けい) - commands

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Formations

一段: Take the 連体形 forms of the verbs and work with their [いる」 or 「える」 endings.

未然形 - 「る」を削除して。
連用形 - 「る」を削除して。
連体形 - 何もしない。
已然形 - 「る」から「れ」に変えて。
命令形 - 「る」を削除して。

五段: Take the 連体形 form of the verb and replace the 「う」 with the appropriate endings below for the other 形 forms.

未然形 - 「あ」
連用形 - 「い」
連体形 - 何もしない。
已然形 - 「え」
命令形 - 「お」

Note: For 五段 verbs in the 連体形 form with only う, the う changes to わ in the 未然形 form. As well, for つ, the つ changes to た in the 未然形 form.

する and 来る, which are the two irregular Henkaku verbs, have their own bases, and are thus conjugated differently.

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未然形 - Mizenkei

Classical Forms:
-ん = classical negative - Note: Appears in literature, not so much speech

Modern Forms:
-ない = informal negative - Note: ある becomes ない, する becomes しない, and 来る becomes 来ない.
-なく = "incomplete" informal negative
  -> -なくなる = becoming negative
-なければ = negative conditional (Read under the -ば section of 已然形)
-ず = negative perfect (Read below)
-なくて/-ないで = negative -て form (Read under the -て section of 連用形)
-「ら」れる = passive or "long" potential (Read below)
-「さ」せる = causative (Read below)
-「さ」せられる = causative passive (Read below)
-「よ」う = informal "long" potential/presumptive (Read below)
  -> -とする = unexpected results
  -> -と思う = considerations
-なかった = negative past (Read under the -た section of 連用形)
-なかったら = negative "past" conditional
-まい = negative "future" (Read below)

-なく form:
A relatively uncommon form, it is basically the in-between before the -ない and -なくて/-ないで forms. Its meaning is similar to the latter, however, it's an incomplete thought in the sense that the sentence cuts off prematurely. It is seldom used, but does exist, and is not incorrect. It is usually seen as a verb compound with なる afterwards (to become or to amount to).

-なくなる form:
This is much more commonly seen than just -なく above. It means "to become to not do [verb]". It adds the implication that something caused you to no longer do something. It sounds weird, hence, an example will do it justice:
パンを食べなくなる。 - I will not be eating bread. (lit. I came to not eat bread.)

-ず form:
This form is used to form phrases such as "having not eaten" or "not having went", etc. You can form it by simply taking the 未然形 of the verb and adding -ず after it. For example:
食べずに来た。 - I came without eating. (lit. I came not having eaten.)
東京に行かず，悲しくなりました。 - I felt sad for not going to Tokyo. (lit. Not having gone to Tokyo, I became sad.)

The irregular verbs する and 来る become せず and 来ず (Kana: こず) respectively.

-「ら」れる form:
This form is separated into two sections: passives, and "long" potentials. Refer to the appropriate sections below.

Passive
Firstly, this form can be used to change a verb into its passive tense, which is roughly similar to repeated speech, in a report-like format. It is slightly more formal than what one would normally say. For example, "He ate the food." would become something like "The food was eaten by him." You can form this by adding -られる onto the end of an 一段 verb in its 未然形 form, or by adding just -れる onto the end of a 五段 verb in its 未然形 form. 「ら」れる itself can then be further conjugated to suit your needs, as it is a verb in itself. For example:
犬が私の晩ご飯を食べられた。 - The dog had eaten my dinner.
彼が海を歩かれた。 - He had walked on the beach.

In addition to the -「ら」れる form, we have the "meiwaku no ukemi" form, which is an evolution of the passive form. You know that this form is being used if a に has been explicitly added to designate an indirect subject/object or a speaker. For example, to make "Sister's car was stolen." into the evolved ukemi form, you would need to use に to relate this phrase to a specific someone or something. To do that, we can make a phrase such as "Sister's car was stolen by somebody."
姉が，誰かに車を盗まれました。 (Kana: あね が だれ か に くるま を ぬすまれました。)

"Long" Potentials
Following this, we can also do the "long" potential form, following the same method as above. This uses the same conjugation completely, but the phrases are a different meaning altogether. Context will help differentiate the two forms. The "long" potential form in the 未然形 is primarily used for only 一段 verbs, so if you see the -「ら」れる form used for a 五段 verb in its 未然形 form, you know for a fact that it is being used passively, as opposed to potentially.

Potentials are verbs that can or could happen, as opposed to simply just happening. For example, if you wanted to say "I might see that movie on the weekend." you would say something like this:
週末に，その映画を見られる。 (Kana: しゅうまつ に, その えいが を みられる。)

Another major usage of the -「ら」れる potential is for interpreting phrases roughly saying "Can you [verb]?" For example:
これを食べられますか? - Can you eat this?

する Note:
する follows no specific method of conjugation for the passive and potential forms, apart from just being known as either される or せられる (passive) and 出来る (Kana: できる) (potential). They resemble completely different verbs altogether, and 出来る (to be able to do [something]) is conjugated similarly to 来る. The choice is entirely up to you whether you want to use される or せられる for the passive form of する.

来る Note:
来る follows no specific method of conjugation for the passive and potential forms, apart from just being known as 来られる for both potential and passive. 来れる can also be used for the potential of 来る.

-「さ」せる form:
This form works almost exactly the same as -「ら」れる. You use －させる if it is 一段, and only -せる if it is 五段. This form is used when talking about actions caused by another force. Usually somebody or something causing somebody or something else to do something. "[somebody/something] let [somebody else/something else] do [verb]." For example:
彼が彼女に彼を待たせた。 - He made her wait for him.
お母さんが子供に晩ご飯を食べさせた。 - Mother made the children eat their dinner.
塗らせて頂きました。 - I was allowed to paint [by somebody else].

As well, this form can be used for asking somebody for a request as well. Roughly in the format of "Let [subject] do [verb]." For example:
線画を描かせて。 - Let me make a sketch.

する and 来る Note:
In the causative form, する becomes させる, and 来る becomes 来させる.

-「さ」せられる form:
This form is the ukemi of -「さ」せる, and is a mix between the two forms above, and roughly means "Somebody or something has been made to do [verb]." It is basically the causative form, mixed with the passive form. Generally speaking, this form is not usually necessary, as -「さ」せる is sufficient. It is conjugated the same as -られる, and still follows the idea that the さ is included if it's 一段. You still use -さられる regardless of whether or not it is 一段 or 五段. For example:
子供がお母さんに晩ご飯を食べさせられました。 - The children were made to eat dinner by their mother.

-「よ」う form:
This is better understood with reference to the 命令形 base
This form is used to show one's possible intention of doing something. Something like "I will go there." or "I shall move there later." The formal version of this is simply the 連用形 form of a verb with -ましょう after it. To use this, you add -よう (for 一段), and -う (for 五段) onto the 未然形 of a verb. One important rule to know, is that 五段 verbs with their -あ endings (from changing it to 未然形), are changed to -お instead. The reason being that -あう sounds very similar to a lengthened お sound. For example:
あなたに待とう。 - I will wait for you.
渋谷駅に行こう。 - I shall go to Shibuya station.

The cohortative form is the same thing. It means something like "Let's go." or "Let's play tennis." Encouragement of sorts. Of course, the formal version is the same thing as well.
行こう。 - Let's go.
テニスをしよう。 - Let's play tennis.

In addition to these forms, you can form a special evolution of sorts. After changing a verb to its respective -「よ」う form, you can add -とする to have the verb mean something like "At the point of doing [verb]." This is only used for something that is actually there. For example:
映画に行こうとした，電話がかかってきた。 - As we were about to go to the movie, the phone began to ring.

Attempted actions or trying to do something can also be made with the -とする evolution. If you add -としている (which is the continuous -て form of する) after a verb in its -「よ」う form, you can say something like "to try and do [verb]". This is derived from the literal meaning of "to do [verb] at the point of doing [verb] continuously," since you're consecutively repeating an action over a course of time, which means that one time was unsuccessful and that you are "trying" to do it another time.

And another evolution, would be -と思う. It means "Thinking about [verb]." For example:
映画を見ようと思います。 - I'm thinking about watching a movie.

On a side note, だ or です would become だろう or でしょう, respectively. This makes a phrase resemble an assumption, like "The water is probably cold by now."
水はもうすめただろう。 (Kana: みず は もう すめた だろう。)

-まい form:
This form is very seldomly used in Japanese. Although not compulsory, conventionally, this form always follows the -「よ」う form of a verb in a phrase, with a か before it. The formal version is simply done by using -ますまい instead.

Means "should I not [verb]"

Basically, this is a type of phrase that indicates that you are possibly not doing an action. There are a plethora of ways to better interpret this form in a conversation, so it is best to know this simply for understanding (incase you ever encounter it). Some examples will help clear things up:
映画に見ようか，見まいか。。。 - To see the movie or not to see the movie...
居ようか，居まいか。。。 - To be or not to be... (lit. To exist or not to exist...)

Note: The 未然形 form is ONLY used with 一段 verbs. For 五段 and Henkaku verbs, refer to the -まい form under the 連体形 section.

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連用形 - Renyoukei

Modern Forms:
-たい/-たくない = desire (Read below)
  -> -たかった/-たくなかった = past desire (Read below)
  -> -たがる = another's desire (Read below)
  -> -たがり = another's desire (Read below)
-たく = "incomplete" desire
-なさい = informal commands
-ます, -ました, etc. = formal -ます form and its other conjugations
-得る (-える) = "short" potentials (Read below)
-たり/-なかったり = verb lists (Read below)
-ながら = multi-tasking (Read below)
-過ぎる (-すぎる) = emphasis (Read below)
-た = past (Read below)
  -> -たろう/-だろう = past "short" potential
-て = Japanese "te" forms (Read below)
  -> Negative Imperatives
  -> Specialized Verb Constructions

Other Usages:
- Verb Conjunctions
- Adjective Conjunctions
- Noun Formations and Conjunctions
  -> Plain 連用形 Form
- Impressions

-たい/-たくない form:
This is the main form used for wanting to do something. Simply add -たい (for wanting to do) or -たくない (for not wanting to do) onto the end of a verb in its 連用形 form. Note: Do NOT use this for another person's desire. Use -たがる instead, which is explained below. For example:
行きたいですよ！ - I want to go!
食べたくない。 - I don't want to eat.

-たかった/-たくなかった form:
Similarly as above, this is the past desire form. "Wanted to do" and "did not want to do." Simple enough, and used the same way. For example:
帰りたくなかった。 - I did not want to return.
あの車を買いたかった。 - I wanted to buy that car.

-たがる form:
This form, used similarly to -たい, is used to denote an action another person wishes to do, and that you know for a fact, rather than yourself. It is very blunt using the -たい form to denote another's action, and may be considered very disrespectful. To use this form, simply use -たがる in place of -たい when talking about somebody else's wish to do an action. For example:
あなたがやりたがるそうですか？ - Does it seem like you want to do it?
あんたが公園に行きたがるそうです。 - Seems like you want to go to the park.

If you noticed, そうです was explicitly added after the -たがる form of the verb. If そうです (seems like) is not added, this is also considered very blunt and can also be considered very disrespectful. Only remove it in cases such as talking to very close friends.

If you know a piece of information about the target speaker (either from him/her or somebody else telling you), you must use -たがる to express their wishes to perform an action. If you are trying to say that somebody wants to do something, but you aren't entirely sure about it (you're making an assumption), you must use -たがり instead, below.

-たがり form:
This is used in contrast to -たがる above, and is also extremely important to know. If you are unsure about whether or not your target wants to do something (you are guessing), you need to use this instead of -たがる. Of course, including the そうです as well. -たがり is only used if you are only making an assumption. For example:
あなたがやりたがりそうです。 - It seems like you want to do it [but that's just what I think].

Although both translate to roughly the same meaning, their intonations are completely different, depending on whether or not you know something about your target. Your target speaker may misinterpret the meaning of this if you do not have the proper usage.

Note: -たいそうです theoretically could be used for another target, but it is a region-oriented kind of thing. Different regions in Japan are suited with -たがるそうです, while others are suited with -たいそうです. You need to personally experience which regions use which in order to have a more appropriate decision. But generally speaking, it is safe to use -たがるそうです for every case.

More information is available below for そうです, under the Impressions section.

-たく form:
A relatively uncommon form, it is basically the in-between before the -たい and -たくて forms. Its meaning is similar to the latter, however, it's an incomplete thought in the sense that the sentence cuts off prematurely. It is seldom used, but does exist, and is not incorrect. It is usually seen as a verb compound with なる afterwards (to become or to amount to).

-たくなる form:
This is much more commonly seen than just -たく above. It means "to become to want to do [verb]". It adds the implication that something caused you to want to do something. It sounds weird, hence, an example will do it justice:
パンを食べたくなる。 - I now want to eat bread. (lit. I came to want to eat bread.)

-たくなくなる form:
This is pretty much redundant, since you could probably just use -なくなる instead. Regardless, it means "to become to not want to do [verb]". For example:
パンを食べたくなくなる。 - I no longer want to eat bread. (lit. I came to not want to eat bread.)

-なさい form:
This is the polar opposite to the 連体形 + な form (which is to tell somebody not to do something). Similarly, it is informal, and is not polite. For example:
その靴を持って来なさい！ - Bring those shoes over here! (lit. Take and come back with those shoes!)

-得る (-える) form:
This is better conjugated with reference to the 已然形 form
In contrast to the "long" potential form in the 未然形, this is the "short" potential form, which exists in the 連用形. This exists only for 五段 verbs in modern Japanese. This verb is intransitive, which means that there is no implied meaning or that its an action that does not have an explicit cause, and thus, the particle が MUST be used instead of を. Adding a -得る to a verb gives it the meaning of "to attain a state of [verb]." or "to be able to do [verb]". This is different from "can do [verb]," which falls under the -「ら」れる form in the 未然系. This form can be created by adding -得る onto the 連用形 form of a verb, remembering that when え is attached to an い, the い is ignored and not said or written. For example:
日の光で，本が読めます。 - I am able to read a book in daylight.

-たり/-なかったり form:
This form is used to create verb lists, by adding -たり (positive) or -なかったり (negative) onto the end at least two verbs in the 連用形 form, followed by する at the end. An example will clear things up:
お友達に話したり，店に行なかったり，映画に見に行ったり，音楽を聞きたりします。 - I am going to be talking to my friends, not going to the store, watching a movie, and listening to music.

Basically, this form creates the idea of "doing (or not doing) things such as [verb] and [verb]" and follows the tense of the する at the end of the entire sentence. Unlike the -て form which follows a sequence and creates a relation between the verb before with the verb after, the -たり form is simply a list, and follows no particular order. You can switch them all around, and it is the same thing. Verbs in the -て form are usually related, while verbs in the -たり form do not necessarily need to be related.

-ながら form:
The -ながら form is used to denote actions you are doing while you are doing something else. Similar to multi-tasking. Simply add -ながら onto the end of a 連用形 form of a verb. For example:
チップスを食べながら，テレビを見ます。 - I'm eating chips while I am watching television.

-過ぎる (-すぎる) form:
This verb form, when added onto the 連用形 form of a verb or an adjective (without the -い or -な ending added on) adds emphasis to it. For example:
あの花はとても美しすぎているんでしょうかな。 - I think that that flower over there is very beautiful. (Adjective)
沢山思いすぎます。 - I'm thinking too much.

One interesting feature, is that you can theoretically transform an adjective to a noun by adding -すぎ onto it. 過ぎる in its plain 連用形 form itself is a noun (refer to Noun Formations and Conjunctions below), so you can logically add it onto an adjective to make it a noun also. Japanese, unlike English, allows for interesting creations like these.

You can also add -ちゃう onto this form to make it both exaggerated and unintentional. Refer to the -ちゃう section below, under the -て form. Basically, a verb in its 連用形 form, plus すぎちゃう. Of course, conjugating ちゃう to your own liking.

-た form:
The past tense form of a verb is very important to know. If you are working with an 一段 verb, simply take the 連用形 form of the verb and add a -た onto it. If you're working with a 五段 verb, this is entirely different, since you do not follow the 形 base system altogether. Instead of taking the 連用形, you remove the ending of a verb (く, ぐ, す, つ, る, う, ぬ, ぶ, む) and you add their respective past tense endings onto them. As well, だ or です becomes either だった (informal) or でした (formal). Read below.

Verbs that end with く or ぐ have their endings removed and have -いた or -いだ added onto them, respectively. For example:
歩く -> 歩いた (to walk -> walked)
泳ぐ -> 泳いだ (to swim -> swam)

Verbs that end with す have their endings removed and have -した added onto them. For example:
話す -> 話した (to speak -> spoke)

Verbs that end with つ, る, or う all have their endings removed and have -った added onto them. For example:
待つ -> 待った (to wait -> waited)
守る -> 守った (to protect -> protected)
言う -> 言った (to say -> said)

Verbs that end with ぬ, ぶ, or む all have their endings removed and have -んだ added onto them. For example:
死ぬ -> 死んだ (to die -> died)
跳ぶ -> 跳んだ (to jump -> jumped)
読む -> 読んだ (to read -> read)

The only verb (apart from the Henkaku) that is irregular when it is conjugated to the past tense is 行く. It becomes 行った instead.

Now, we have two more special constructions of the past tense. -たろう/-だろう and -たら.

-たろう/-だろう form:
These two forms roughly give the meaning of "will probably have done [verb]" in the past tense. It is done by taking a verb in its past tense (refer to -た above), and by adding ろう. For example:
その本はもう，読んだろう。 - I probably already read that book.

-なかった form:
Was previously mentioned under 未然形
The negative past tense of any verb (not needing to follow the rules above) can be formed by adding -なかった onto the 未然形 form of the verb. As well, you can add -ろう or -たら as applicable. For example:
彼は時間に帰らなかった。 - He didn't return on time.

-て form:
The -て form is very difficult to explain. It is essentially used to conjoin phrases. You can form this exactly as you would form a past tense verb, except that the -た is a -て instead. Thus, refer to the conjugation rules for -た above.

There are three main uses for the -て form. Action chains, negative imperatives, and special verb constructions. First off, action chains help link two verbs together. The tense of the first (and any verbs following afterwards) follow the tense of the last verb in the sequence. The usage is similar to the -たり verb list, except that this is sequenced, and has a certain order to it. For example:
映画を見て，本を読みます。 - I am going to watch a movie and read a book.
図書館に行って，お友達が会って，学校の事を話している。 - I am going to the library, meeting a friend, and talking about school-related stuff.

Now, you are allowed to leave a -て based phrase open-ended, which is an entirely different thing altogether. Refer to the ください explanation for special verb constructions below.

-なくて/-ないで form:
Was previously mentioned under 未然形
This form is simply the negative of the -て form. You can form it by simply taking the 未然形 of the verb and adding either -なくて or -ないで after it. It does not matter which you choose. For example:
行かなくて/行かないで。 - Do not go.
朝ご飯を食べないで，学校に行きました。 - I didn't eat breakfast and went to school.

Negative imperatives somewhat resemble commands, but their sole purpose is not to command, but more to inform. They are formed by taking the negative -て form, adding the particle は, and adding either 駄目 (だめ) or いけない. For example:
食べなくては駄目。 - You cannot eat it.
行かないではいけない。 - You cannot go.

A brief note for the -て form, usually verbs that directly follow a verb in its -て form, unless it they are extremely uncommon, are usually written in plain hiragana instead of kanji.

Specialized Verb Constructions

Lastly, we have the specialized verb constructions, which are very frequently used in speech. These are formed when speific verbs are added onto a -て based sentence, rather than having one verb be the end. Like the library example above, instead of 話します, 話している was used. 話して and いる. When verbs are added onto the end of a -て based sentence, special meanings are created. The ones listed below are very commonly used in Japanese, and are essential to remember. And on a important note, these verbs can be conjugated in any way you like to provide for the tense of the verbs preceeding it. They may even be conjugated back to a -て form, for usage with ください, for example.

ください - Formal requests:
If you do not know already, you can use ください to show that you wish to ask of somebody to do something politely. You may also use お願いする as well. It does not make much of a difference. Simply add it after a verb in the -て form. This effect applies to all the verbs in the same sentence.

A good note, if the last verb in a sentence ends with only an open-ended -て verb, as in, the sentence ends with simply a verb in its -て form, it means that it is an informal request. For example:
ここに行って，私に話して。 - Come here and talk to me.

The ください or お願い is implied, but is instead changed to an informal (and sometimes quite direct) request of somebody. Kind of like "Please sit." changed to "Sit."

来る, 行く/ゆく - Direction-based actions:
These are used to add changes of time into a -て phrase. As in, "going to become [verb]" or "[verb] is arriving," etc. Of course, these are broad translations, and are not necessarily the case for every verb. 来る would be used for phrases that are "coming towards" the speaker, while 行く or ゆく are for phrases that are "heading away" or leaving the speaker. For example:
夏になってきた。 - It has become summer. (lit. It has come to become summer.)
夜になっていく。 - It is becoming night.

There is also a slight nuance with using 行く. You use 行く when you are trying to indicate something that is undesirable. This means, you somewhat do not wish for something to happen, but it is going to occur (or is occuring) anyway. This is not said on the surface, as it is implied.

As well, since 行く and 来る are very common verbs, they remain in plain kana when added onto a -てform of a verb.

置く - Implied reasons:
置く (おく) is used when performing an action and letting it continue happening for a some reason. For example:
電気を付けて置いてください。 - Please turn on the lights [and leave them on for whatever reason].

見る - Trying out actions:
When 見る is added onto a -て verb, it gives the meaning of "to do [verb] to see what happens" or "to try [verb] to see what it's like." For example:
寿司を食べて見ませんか？ - Won't you try eating some sushi? (lit. Won't you eat some sushi to see what it's like?)

Of course, depending on the context, that could also be used to tell the target to try the sushi in order to see if he/she likes it.

しまう - Accidental actions:
This form is used when accidentally doing somebody, usually with the idea that you didn't mean to do it on purpose. Roughly speaking, this means "I [accidentally] did [verb]." Another way to think of this could be an action being an accident, like missing the bus on the way to school. Also, just because an unintended action occurs does NOT mean that it is implied. Thus, according to the context, both を and が can be used. For example:
テレビを壊せてしまった。 - I [accidentally] broke the television.

The "soft" informal version of しまう is -ちゃう/っちゃ/じゃう. Unlike しまう which can be added onto the end of any -て form verb, ちゃう and its variants depend on the -て form preceeding it. This is formed by replacing -てしまう or -でしまう entirely by its -ちゃう variant.

If a verb's -て form ends in just -て, you use -ちゃう. For example:
びっくりしちゃった。 - I was [unexpectedly] surprised.
時計に見ちゃった。 - I [unintentionally] looked at the clock.

If a verb's -て form ends in -って, you use -っちゃう. For example:
あそこに行っちゃった。 - I went over there [by accident].
沢山時間が待っちゃった。 - I waited a long time [by accident].

If a verb's -て form ends in -で, you use -じゃう. For example:
違う言葉を読んじゃった。 - I [unintentionally] read the wrong word.
ずっと遠い島に泳いじゃった - I [accidentally] swam to a really far island.

-ちゃう can also be used to command, and is done by simply adding changing the -て form of a verb into its respective -ちゃう form, removing the う, then adding 駄目 (だめ) or いけない. For example:
食べちゃ駄目！ - You must not eat it!
行っちゃ行けない！ - Do not keep going!

Another informal version of しまう is ちまう/じまう, which could be considered the "rough" informal version of it. While ちゃう and its variants are a bit softer and more casual, ちまう and じまう are more serious instead. They are formed using the same idea as above; -ちまう for -て, -っちまう for -って, and -じまう for -で.

あの女の子はちょうど落ちちまった。 - That girl over there just [accidentally] fell down.

いる & ある - Results, Habits, and Continuous actions:
いる and ある are used very frequently in Japanese. They are used to describe resultant actions, habits, and continuous actions. A continuous action does not necessarily have to be habit, and a habit may be just for one moment, rather than a continuous one. They are slightly different.

ある is only used for resultant actions that have implied meanings in them. Thus, を is always used. If there is a resultant action that does not have a reason to it, use いる instead. For example:
電車を止めてある。 - The car stopped [because something caused it to do so].

The implied meaning is that the car has stopped because something or someone had stopped it, but this is not explicitly said. If いる was used in place of ある, it would have simply been "The car stopped." This could have been a habit or a continuous action, but that would not make too much sense in this case, unless the driver constantly keeps stopping the car for no apparent reason. Though, if the reason is really because of a habit, you would use いる instead, which is explained further below.

いる is used for habitual acts and continuous actions, with or without implied reasons in them. Habits are not to be mistaken for continuous actions, as they are a one-time thing at that specific moment. They are not continuous. Though, since they are both made exactly the same, it is not wrong to assume both of them as simply being continuous. A habitual act could be defined as a continuous action, but just in another sense. Looking at the examples below, you can tell that they resemble continuous actions, but are really just habits. And as always, を is used for phrases with implied reasons, and が is used for phrases without implied reasons.

Examples of habits:
よく新聞を読んでいます。 - I read lots of newspapers [because I am used to them]. (Implied)
そのドアがよく軋っています。 - That door keeps creaking [for no apparent reason]. (Not implied)

Examples of continuous actions:
今，朝ごはんを食べています。 - I am currently eating my breakfast.
犬があそこで寝ていました。 - The dog was sleeping over there yesterday.

毎週，好きな公園に行っている。 - I go to the parks I like every week.

One brief note, when in speech, -ている becomes simply -てる. It is sometimes still written with the い, but it is not explicitly said in conversations. For example, 食べていた could appear as such when it is written, but would only sound like 食べてた in a conversation.

Finally, a mixture between いる and an informal request can be done to make yet another special verb construction. If you conjugate a verb into its -て form and add いる in its -て form after it, you can say something like "please do [and keep doing] [verb]". And as explained directly above, for this one special construction, you do not write or say the い in いて. For example:
ほらほら，ちょっと待っててくれ！ - Hey hey, please wait [and keep waiting] for a moment
皆，見てて下さい。 - Everybody, please look [and keep looking].

Verb Conjunctions

Verb conjunctions in Japanese are made by simply taking the plain 連用形 form of a verb, and adding another verb onto it. For example:
歩く + 回る = 歩回る (Kana: あるき まわる)

That example above uses the verbs 歩く, to walk, and 回る, to go around. You take the 連用形 of 歩く, which is 歩き, and you add on 回る. Once these are merged together, you get a compound that means "to walk in circles."

There are tons of different verb conjunctions you can do, since there are thousands of verbs in Japanese. You have to figure out compounds yourself by personal experience. For this specific case above, you cannot do the compound backwards, as it does not make any sense. To figure out the correct order of compounds, you need to know how the language works. Verb conjunctions are simply a concept that depends entirely on how much you know, and cannot be fully explained as it is too expansive. As well, some verbs are extrapolated when compounded, and can sometimes give very abstract "outside-the-box" meanings that you would usually never think of. A good grasp on the Japanese language will help determine the meanings to these.

As well, one practice that you should do is to remove the okurigana from the compounded verb, which would be the き in this case, as seen above (歩き回る > 歩回る). The compound verb is still read exactly the same as if the き is there.

Though there are thousands of different combinations that could be made, but some commonly used ones are below:

直す (Kana: なおす) - to fix/correct/repair/etc.
 - When compounded- it gives the idea of redoing a verb. For example:
書き直す (Kana: かき なおす) - to rewrite
やり直す (Kana: やり なおす) - to redo

込む (Kana: こむ) - to go into/enter/crowd (in on)/fill up/etc.
 - When compounded, it could mean the act of entering into something, or to be involved/entangled in something. For example:
入り込む (Kana: はいり こむ) - to go into [somebody's home/etc.]
巻き込む (Kana: まき こむ) - to be involved with [something] - Note: 巻く means to roll/wind, but this verb is extrapolated when compounded to 込む.

出す (Kana: だす) - to come out/exit/etc.
 - When compounded, it gives roughly the reverse meaning of 込む above. For example:
言い出す (Kana: いい だす) - to start a conversation - Note: This is one of those compounds that are extrapolated, and are very unexpected. This does NOT mean to exit a conversation. If you assume that 言い stands for 'words', and 出す stands for "coming out," added together, they mean "words coming out," which signifies the start of a conversation.

切る (Kana: きる) - to cut
 - When compounded, it could mean anything from cutting physically to cutting abstractly. For example:
言い切る (Kana: いい きる)- to assert while cutting someone else off - Note: This is different than to cut talking or to shut somebody up, as that usually results in a continued discussion after somebody is cut off. This compound in particular completely ends a discussion, not allowing any continuation afterwards.

Adjective Conjunctions

Adjective conjunctions are very easy in Japanese, as there are only three common compounds used in modern Japanese. The others are no longer in common use. These three are below, and they are compounded exactly the same as a verb compound (take the 連用形 of a verb and add on the adjective).

易い (Kana: やすい) - easy
難い (Kana: にくい) - hard/difficult
難い (Kana: がたい) - hard/difficult

Examples:
読み易い本 (Kana: よみ やすい ほん) - An easy to read book
分かり難い歌 (Kana: わかり にくい うた) - A hard to understand song
言い難い事 (Kana: いい がたい こと) - Something that is hard to say

Note: It is entirely up to you whether or not you wish to drop the okurigana in an adjective compound.

Now you may be wondering, why are there two adjective readings for hard? This is simply because がたい is classical Japanese, and is no longer used except for one major very commonly encountered situation, which is for "Thank you very much" (有り難うございます). For simplicity, it is safe to read it as にくい for all cases, as there are very few occasions when you would need to use がたい.

Noun Formations and Conjunctions

Noun conjunctions are also quite easy, as it is also made the same as a verb or adjective conjunction. You just simply take the 連用形 form of a verb and add a noun onto the end. This creates a new noun, which gives it a new meaning. A good example would be a Japanese kimono, which is actually compounded from 着る and 物 to form 着物. 着る (きる) is to wear, so "to wear" and "thing" added together is a thing you wear. Another example:
彼は公園に行きたい人そうですね？ - He's the type of person who wants to go to the park, isn't he? (lit. He is a person who wants to go to the park, right?)

Two kinds of nouns can be formed using the 連用形. One is the plain noun, which is simply made by taking the plain 連用形 form of a verb. Another is the "method-of-doing" or "way-of-doing" noun, which is made the same way as a noun conjunction, but by adding 方 (かた) after it.

The plain nouns are quite simple. You're basically changing a verb directly into its noun form. For example, 話す, to speak, would become 話 (はなし), which is a conversation.

The "method-of-doing" or "way-of-doing" nouns are also quite simple. For example:
読み方 (Kana: よみ かた) - Method/way of reading
お箸の使い方 (Kana: お はし の つかい かた) - Method/way of using chopsticks
戦争の仕方 (Kana: せん そう の しかた) - Method/way of doing war

Impressions

Impressions in Japanese are done with そうです. This gives the meaning of "seems like [verb]" and is used usually as a polite marker. そうです is usually added onto a verb in the 連用形 form, and is seldom (if ever) used with another 形 form. There are three other ways to describe an impression, but they will be explained later. There are no specific rules to this usage, other than just adding a そうです after a phrase with a verb ending in the 連用形 form. For example:
おじいさんがまだ歩けそうです。 - Seems like grandfather is still able to walk.
彼はひとつだけやりたいそうです。 - Seems like he wants to do only one thing. (Note: Read about -たいそうです in the -たがる section above.)

Negative impressions using そうです can be done via two methods. If you want to say "it doesn't seem like [verb]," you just add そうじゃない instead. If you want to say "seems like it isn't [verb]," you use the 未然形 form of a verb, and add なさそうです. For example:
あんたが行けそうじゃない。 - It doesn't seem like you can go.
彼女が分からなさそうです。 - Seems like she does not understand.

Sometimes this can also mean "at the point of [verb]" as well. This is different than from -とする, since that one is only for something that actually exists. そうです is used for just impressions or assumptions.

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連体形 - Rentaikei

Modern Forms:
-な = negative imperatives - "Do not do [verb]."
-まい = negative "future" (Read below)

Other Usages:
- Noun Formations
- Presumptives
  -> Plain 連体形 Form

-な form:
Negative imperatives are basically negative commands. That is, you're telling somebody else not to do something. "Do not do [verb]." For example:
そのドアを開けるな。 - Do not open that door. (lit. That door opens not.)

-まい form:
This form is very seldomly used in Japanese. This is formed by adding a -まい directly after a verb in its 連体形 form. The formal version is done by adding -まい onto the end of a verb in its formal -ます form.

Basically, this is a type of phrase that indicates that you are possibly not doing an action. There are a plethora of ways to better interpret this form in a conversation, so it is best to know this simply for understanding (incase you ever encounter it). Some examples will help clear things up:
公園に行こうか，行くまいか。。。 - To go to the park, or not to go to the park...
お友達に会いましょうか，会いますまい。。。 - To meet my friend, or not to meet my friend...

Note: The 連体形 form is ONLY used with 五段 and Henkaku verbs. For 一段 verbs, refer to the -まい form under the 未然形 section.

Noun Formations

The plain 連体形 form of a verb can be prefixed onto a noun just like an adjective (predicatives). It gives the feel of an adjective, and is used for describing words in more detail. You just simply attach the verb directly before a noun. For example:
コーヒーを飲む人 - A person who drinks coffee

The negative of this can be formed by taking the informal negative form of a verb (refer to the 未然形 section), and suffixing it with a noun. For example:
飛ばない鳥 - A bird that does not fly

Presumptives

Presumptions can be alternatively formed (in contrast to the -「よ」う form in the 連用形) by simply adding でしょう (formal) or だろう (informal) directly after a verb in its plain 連体形 or dictionary form. It implies that something will probably happen. For example:
食べるだろう。 - Let's eat.
この車は走るでしょう。 - This car will probably run.

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已然形 - Izenkei

Modern Forms:
-ば = hypotheticals (Read below)
  -> なら「ば」 = hypothetical of だ/です
-たら = "past" hypotheticals (Read below)

-ば form:
The -ば form is used to basically say "If you do [verb], something will happen." It is very important, and is very easy to form. Simply add -ば onto a verb in its 已然形 form. For example:
ケーキを食べれば，おなかが痛いんでしょう。 - Your stomach will probably get sick if you eat cake.

An even more important note, the -ば form of だ or です is なら. It means something like "If it is this," and is completely dependant on what preceeds it. -ば can be optionally added after なら for politeness, and has no effect on the meaning.
それだけならば，まだ十分持ちません。 - You won't have enough if it's only this.

The negative version of the -ば form is -なければ, which is attached onto the 未然形 form of a verb. It is used the same way as above. As well, -なければ can also be used as one of the many ways to say "I have to do [verb]." Refer to the "I have to do [verb]" Phrases in the Other Essentials section below.

-たら form:
"Assuming you did [verb], ..."
This form is used to make hypothetical pasts, which roughly means "should [subject] have done [verb], ." or "If [subject] does [verb]," It is done by taking a verb in its past tense (refer to -た above), and by adding ら. For example:
町を行ったら，面白い見物をいっぱい見ました。 - Should you have went around town, you would've seen many interesting sights.
東京に行けたら，一緒に行きいました。 - If you could've gone to Tokyo, we could've gone together.

The negative version of the -たら form is -なかったら, which is attached onto the 未然形 form of a verb. It is used the same way as above.

Imperatives

For 五段 verbs, you can issue commands to someone with the plain 已然形 form. More details are available in the 命令形 imperatives explanation below.

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命令形 - Meireikei

Modern Forms:
-ろ = imperatives (Read below)
-よ = advisory (Read below)

-ろ form:
For 五段 verbs, use the plain 已然形 form
This form is used to issue commands in Japanese. For 一段 verbs, you simply add -ろ onto the end. For 五段 verbs, you simply use the verb in its plain 已然形 form. For example:
寿司とてんぷらを食べろ。 - Eat the sushi and tempura.
新聞を買って行け。 - Go and buy the newspaper.

する and 来る Note:
For the irregular Henkaku verbs, you use しろ and 来い respectively.

-よ form:
「よ」お「う」: +よ「う」 for ichidan, and +う for godan
The -よ form is used to advise people of something. It's similar to a command, but not a strong one. It may also be usedto express one's possible intention in doing something. You simply take an 一段 verb in its 命令形 form and add -よ onto it. There is no advisory form for 五段 verbs; this conjugation is explained in further detail under the 未然系 section. For する and 来る, you use せよ and こよ respectively. For example:
その映画を見よ。- You should watch that movie.
そのクラブを参加せよ。- You should participate in that club.

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Other Essentials

-つもり Noun Formations:
The noun つもり can be added onto any verb in any form to make it mean something like "to plan to do [verb]." For example:
東京タワーに行くつもりです。 - I am planning to go to Tokyo Tower.
その事をならないつもりですよ。 - I am not planning to become like that.

"I have to do [verb]" Phrases:
Japanese does not have a specific conjugation for making phrases that mean "I have to do [verb]." In order to circumvent this, you use a special phrase format that gives an implied meaning of requiring to do something. You can achieve this by either saying (literally) "With not doing [verb], I cannot go/become." (Method 1) or "I cannot go/become if I do not do [verb]." (Method 2).

Of course, these are not the only methods you can use to say "I have to do [verb]" in Japanese. There are many more ways to do so as well.

Method 1:
You can do this by simply following the negative form of a verb with -と行ける or -となる in their negative form (both formal and informal are fine). For example:
飲まないと行けません。 - I have to drink. (lit. With not drinking, I cannot go.)

Method 2:
You can do this by simply following the -なければ form of a verb in its 已然形 base with either 行ける or なる in their negative form (both formal and informal are fine). For example:
その映画を丁度見なければならないんです。 - I just have to see that movie. (lit. Just, I cannot become if I do not see that movie.)

Obviously, it does not make too much sense if you use 行く with 行ける and なる with, well, itself. That's why, for those two, you always use the other one instead.

The reason why either 行ける or 生る is used is quite simple. When you conjugate them into their negatives, they become "cannot go" and "do not become (cannot become)" respectively. If you take any verb like 食べる for example, change it to its -なければ form, and attach either 行けない or ならない onto the end (both informal), it becomes either "食べなければ行けない." or "食べなければならない." If you translate them literally, they mean "I cannot go, if I do not eat." and "I cannot become, if I do not eat." Hence, they make perfect sense, since you need to do something in order to achieve your goal. Hence the idea behind "having" to do something. Of course, these are the two most frequently used verbs to achieve the idea of "having" to do something, and they both mean the same thing in this special case. Generally speaking, なる is sufficient enough to be used for all cases, except for itself.

一段 Verbs in the 未然形/連用形 form + える:
This, also called the Chinese influenced potential, is roughly translated as meaning "to have [verb] occur." This is not exact, and does not fall under either of those bases. Since Chinese influenced potentials usually have their own abstract meanings derived, there isn't one good generalization for its meaning. For example, a very popular verb, 見る can be changed to 見える, which means "to be seen."