Transgender or Transexuality is an umbrella term for anyone whose internal experience of gender does not match the sex they were assigned at birth (normally based on first and secondary sex charateristics). Transgender people may experience discomfort or distress due to their gender not aligning with their sex, and therefore wish to transition to being the gender they identify with.
Some transgender people feel this way from a very young age, while others go through a period of questioning before realizing they are transgender. Transgender people can be men, women or non-binary. They can have any sexual orientation, express their gender through their appearance in any way, and may or may not fit into society's views of gender.
People whose sex corresponds to their gender identity are referred to as cisgender.
There are a wide range of terms used in reference to transgender people, and the definitions of words often vary over time, or between different groups of people. it is always important to check in with individuals which words they prefer to use rather than to assign them labels they may not be comfortable with.
Generally, all discussion of transgender people is focused on gender identity. For example, a trans man is someone who views themselves as a man and was assigned female at birth. It is his internal experience (as a man) which determines how he is described, not the way he is seen by society. Similarly, a trans woman views herself as a woman and was assigned male at birth. This can confuse those who are new to discussions of transgender identity, but it's an important distinction.
This distinction is based on the understanding that gender and sex are separate, where 'gender' means internal experience, and 'sex' means the attributes of the body. Therefore, a woman (gender) can have a penis and XY chromosomes (sex), but this does not affect her self-identity as a woman, except for the possibility that she was raised to see herself as a man.
Terms such as "male-bodied" and "female-bodied" are often seen as inappropriate because they confuse gender with sex. A trans woman is a woman, and therefore her body is female because it belongs to a woman. Instead, the terminology "assigned male/female at birth" is used to indicate whether a person is born male or female. This terminology also acknowledges that gender varies between societies, and some cultures recognize three or more genders.
It is worth noting that some people are born with sex characteristics that cannot be easily classified as either male or female. This is known as being intersex, and many intersex individuals are unaware of their condition. Those who are not intersex are referred to as dyadic.
The gender binary refers to the idea that there are only two genders, man and woman, and that everyone can be categorized as one or the other. However, many people feel that their gender identity is non-binary and cannot be described as either of these identities. Another term used for people who fall outside the gender binary is genderqueer, which is often used to imply a desire to change the norms of gender.
The gender spectrum on the other hand is the idea that gender isn't binary but a continuum. At it simplest is a line between male and female. The next step up is a 2D pane with male and female on the axis. The next step is adding in Aporagenders(genders not related to male or female) each on their own axis. The final step is Gender Field theory where gender is a N-dimensional field. For more on the different theories of gender see Models of gender identity.
Transition is any action a transgender person takes in order for the external world to better recognize and reflect their internal gender. This can range from asking people to use different names and pronouns, to a change in dress or appearance, to extensive surgery. The three main forms of transition are social, legal, and medical, although all of these are broad categories which can reflect dozens of different possible actions.
Transgender people have dysphoria (feelings of distress) arising from their sex characteristics not matching their self-image and/or being seen and treated as the wrong gender (misgendered). This dysphoria may be referred to by the medical term of Gender Identity Disorder, for which the correct treatment is considered to be transition, accompanied by any necessary support to achieve the desired state.
Some transgender people have gender euphoria (feelings of elation) from making or thinking about their body, gender expression and/or being seen and treated as prefered gender.
Every transgender person has different desires for what they want (or do not want) to include in their transition, including surgery and other medical procedures. Transgender people who do not plan to have surgery are sometimes referred to as non-op; transsexual is sometimes used to refer to only those who do. It is important not to make assumptions about what is, was or will be involved in any individual person's transition.
Some transgender people are aware of their condition as children and begin transitioning then, such as by taking puberty blockers to delay the development of sex characteristics until they are old enough to be allowed to medically transition. However, many attempt to reconcile themselves with living as their assigned gender, and only transition later in life when they realize they are not happy with the way things are. This may involve a period of questioning in which a person is uncertain of their gender identity, and wishes to explore before settling on a label for themselves.
Even after transition, transgender people may not want to reflect societal stereotypes of their gender identity. For instance, a trans woman can be masculine, a tomboy, work as a mechanic, or hate wearing dresses - just as a cis woman can do any of those things.