Transgender people are people who have a gender identity or gender expression that differs from their assigned sex. Transgender people are sometimes called transsexual if they desire medical assistance to transition from one sex to another. Transgender is also an umbrella term: in addition to including people whose gender identity is the opposite of their assigned sex (trans men and trans women), it may include people who are not exclusively masculine or feminine (people who are genderqueer, e.g. bigender, pangender, genderfluid, or agender). Other definitions of transgender also include people who belong to a third gender, or conceptualize transgender people as a third gender. Infrequently, the term transgender is defined very broadly to include cross-dressers, regardless of their gender identity.
Being transgender is independent of sexual orientation: transgender people may identify as heterosexual, homosexual, bisexual, asexual, etc., or may consider conventional sexual orientation labels inadequate or inapplicable. The term transgender can also be distinguished from intersex, a term that describes people born with physical sex characteristics "that do not fit typical binary notions of male or female bodies".
The degree to which individuals feel genuine, authentic, and comfortable within their external appearance and accept their genuine identity has been called transgender congruence. Many transgender people experience gender dysphoria, and some seek medical treatments such as hormone replacement therapy, sex reassignment surgery, or psychotherapy. Not all transgender people desire these treatments, and some cannot undergo them for financial or medical reasons.