Transgender / Trans is a term used to describe a person whose gender identity differs from the sex birth certificate. Gender identity is a person's internal, personal sense of being a man or a woman (or someone outside of that gender binary). For transgender people, the sex they were assigned at birth and their own internal gender identity do not match.
People in the transgender community may describe themselves using one (or more) of a wide variety of terms, including transgender, transsexual, and transperson. Trans Woman refers to a person who has transitioned from a male to a female (MTF). Trans Man refers to a person who has transitioned from a female to male (FTM).