Trill is a planet, and a society, who have never been in a civil or interstellar war. They attained globalization remarkably fast and their development of technology followed suit, and all of this was due to the second race of species that lives on their planet, symbionts. Symbionts are biologically immortal (they can be killed through physical means, but their telomeres do not degrade with age) and they can integrate themselves with the humanoid population through a process called Joining.

This integration imbues the Trill people with a sense of greater picture, which has influenced their culture and in turn, even their education. One aspect of Trill education that exists planet-wide is called zhian'an, from the Trill zhia, meaning, to accept. The phrase zhian in full, is the word for Joined. This etymology sheds a little light unto how Trills perceive the Joining process; that the host (humanoid Trill) must accept the symbiont in order to coexist together.

Even the Trill language has evolved pronouns to distinguish between the singular-I, singular-we, Joined-I and Joined-We. Trills speak GENZARI, a globalized esperanto-style constructed language (at first, though it is now natural), and there are regional dialects of Trill aside from that which are mostly mutually intelligible with one another through the understanding of Genzari. Like Rigelian, Genzari features psionic classifiers that function similarly to "tone tags" or punctuation in Standard written speech, but which are verbally inflected.

The Genzari accent sounds a little similar to the MALAYSIAN ACCENT or the SINGAPOREAN ACCENT on Earth, but with key differences vowels (Genzari vowels tend to be diphthong or elongated) and in /th/, /d/, /t/ and /r/. /r/ in Genzari is GUTTURAL.

Trills can struggle with words that contain /x/ and /z/, coming across as djee/zjuh or shee/chee, or separated as /ks/. For instance a Trill saying the sentence "I threw an exceptional fish back in the river," would sound like, to a prominent Genzari accent: /eye/ /t/hrhew/ /eɪn/ /assep'shunaal/ /feɪsh/ (or feɪch) /bæk/ /inta/ /hrævar/. A less prominent accent might say I thrhew en eksep'shunel fesh bæk inda rhivar.

The Symbiosis Commission receives thousands of applications for Initiate training every year, and usually only about one hundred are accepted each year into Initiate training. Initiate training is a much deeper, more-inclusive type of zhian'an that involves, among other things, telepathic conditioning, adaptive meditation, intense psychiatric and physiological evaluations, et al. In order to be accepted into the Initiate program, candidates must prove that they can contribute something to the symbiont’s gestalt experience of the universe. It is not uncommon for candidates to have completed post-secondary degrees, or to already have careers of their own by the time they apply for Initiate status.

For Trill children, zhian'an in school more closely deals with concepts such as conflict resolution, truth, history, and xia'pan; the ability to hold two consecutive thoughts at once without entertaining either. Behavioral dialectics is baked into every part of Trill society, and Trills are trained to endure massive amounts of overwhelming emotional and neurological input from birth, typically participating in deeply comprehensive trauma-informed personality therapy from birth.

This is what allows the Trill to exist as a society in a state of continual peace, as they are taught structured methods of meditation, acceptance and conflict resolution that prevents the type of violence and bloodshed we see in other world histories. This is in addition to the functional neurological structure of a Trill, which is primed to experience a vast quantity of psychological stimulus, and thus makes Trills more emotionally alien than other species in the Federation.

Rather than a Vulcan who suppresses their natural emotional responses (and Vulcans, despite their reliance on logic, have a long and bloody history) in favor of what they deem to be logical, Trills incorporate emotional awareness and structured emotional expression into every aspect of their society. Trills are trained from a young age to engage emotionally with their peers, and to reflect and understand how their actions affect those around them, and to express how they're being affected.

Nevertheless, significant emotional responses are not common in Trills, who tend to accept the reality of a situation first, before then moving through their own internal processes and reactions. Crying, wailing, screaming, and raising one's voice are simply not natural to a Trill, and they are very even-keeled as a whole. For example, a Trill might say aza'eæ (hello'anger-classifier) or aza'kax (hello-'distaste-classifier) or aza'xi (hello-'exclamation!-classifier) without much changing the intonation or volume of their voice, as their language communicates these concepts very well otherwise.

This doesn't mean that Trills can't have strong emotional responses, but they are trained in managing a high level of distress starting in childhood, in preparation for Joining and in participating in greater Trill society, so meltdowns are much less likely. This, along with Trill’s geological instability, focused the people on learning to tame their world, rather than on conquest. Even after industrialization and the advent of technology, this type of training still exists today, with children learning to assemble tiyala puzzles and engaging in mock debates.

For those Trill who choose to pursue Joining, the importance of preserving the sacred connection of host and symbiont is paramount to an Initiate’s success in completing the Initiate program. It is the Joined host’s responsibility to ensure the symbiont experiences new history, explores new ideas, and lives new, and improved lives; which is just one of the reasons why re-association is considered taboo. After all, the purpose of Joining is to enhance the symbiont’s awareness of the universe, and reliving the same lives, and relationships, is detrimental to that process.

Joined Trill can sometimes come off as seeming a little more arrogant or entitled than their unjoined peers, and Trills who don’t aspire to Joining are sometimes referred to, usually in a juvenile context, pejoratively as lajah, or unfit. There is some stigma regarding rejection from either a Joining attempt, or from the Initiate program altogether, and many Trill consider this a source of shame if it happens to them.

It should be noted that prior to the 24th century, the knowledge of Trill Joining and symbionts was kept a closely guarded secret by the Symbiosis Commission, so those Trill who did travel off-world were held to a strict code of confidence, in order to protect the symbionts from outside influence, and to prevent others from trying to steal or otherwise aggress against the symbiont population. The Trill planet revolves somewhat slower than Earth and one full revolution on Trill is 50 hours, making the ratio between Trill and Earth days roughly 2:1.

Physiologically the Trill differ in a few ways from other humanoids: their DERMAGLYPHS, a pattern of spots that sweeps along the arch of the eyebrows, down the sides of the neck symmetrically, across the shoulders and then across the abdomen, right down the sides of their legs, facilitate the transfer of isoboramine, a neurotransmitter that permits communication between host and symbiont. Trills are also the only other species in the Federation other than Vulcans who can perform a synaptic pattern displacement.

Symbionts rest inside the perimacrovial membrane, a unique structure in Trills that makes up a significant portion of their thoracic cavity that opens with forceful traction applied on either side of the outward macrovial seam located in the lower abdomen. These days it is a simple surgical procedure to be Joined-there are no pain receptors in the area which means it can be done while awake, but in the days of past, symbionts were transferred of their own momentum, and through manual manipulation of the membrane.