Mongo DB unlike relational database, is a JSON-like document oriented database. The mongo shell is an interface used to add, query, update, etc data.
Here’s a cheat sheet of Mongo Shell commands often used:

1 Login to the server
2 Type `mongo` to get the mongo terminal

  To create a new database:
   use database_name

 To See the list of all database present:
    show dbs

 To use the database you want to use:
    use <dbname>

 To see all Collections(group of MongoDB documents) in current database:
   show collections

 To see all the data present in db:
   db.collectionname.find({}).pretty()

 To count the existence of a particular data:
    db.collectionname.find({"title" : “Some data”}).count()

 To find a document:
    db.collectionname.find({"title" : “Some data" }).pretty()

  To update a single document:
     db.collectionname.update({"title" : “Some data" }, { $set: {"title": “New data”}})

 To update multiple documents at once:
     db.collectionname.update({"title" : “Some data" }, { $set: {"title": “New data"}}, {"multi": true})

 To remove any document:
    db.collectionname.remove({"title" : “Some data”})

 To remove documents not equal to “Some data”:
    db.collectionname.remove({"title" : { $ne : “Some data"}})