@Lekimno "Transgender people have a gender identity or gender expression that differs from the sex that they were assigned at birth. Some transgender people who desire medical assistance to transition from one sex to another identify as transsexual." - Wikipedia.
This definition may be written by them but its not vary accurate. From my understanding and from claims in research They claim that their brains chemicals and reactions are like that of the sex they identify as, hence why they think they are trapped in the wrong sexs body. I find it weird how that definition uses the word "assigned" as if its something arbitrarily set at birth when common sense says that is not the case especially given how few of them there are, its not arbitrary at all. What they all call themselves varies from person to person, some of them find some of those terms to be derogatory so i find that quote from wikipedia to be inaccurate. Which given that anyone can edit those articles, being inaccurate is likely especially since there are not any scientific sources for such things, usually opinions are left out of wikipedia articles.
In the past it was considered a mental illness, but there are some trans people that are not interested in surgery and others that are. What i find interesting is that there is a mental illness where people feel like "that part of my body isnt mine, it shouldnt be on me" and some of them will try to hurt themselves to remove that limb or to force a doctor to remove it. While im sure its no fun to be in their situation, i find it interesting that some of them feel the absolute need to change their sexual organs to match how they feel, while others would never dream of doing that and are more then happy to live with their body as it is. Its also interesting that we teach people to accept their body how it is and to be happy with it while also living in a healthy way, but trans people are encouraged to do the opposite, to reject it and to change it through surgery. Though in general while i think people should be able to live how they want, i think many people that opt for plastic surgery are out of their minds, though there are many cases where its done to restore some kind of damage not just to modify their body to fix some imagined problem(like for instance, i saw someone that made their cheek bones so large they look more like an alien rather then a human, and they did so because they thought it made them look "pretty" like a normal person, that person to me seems to have a mental illness but they were still allowed to get the surgery despite their view of reality not matching reality itself. Some of those people even risk body parts falling off due to loss of blood supply from too many surgeries, i cant imagine the risk being worth it, yet they keep altering themselves).