Definitions
WHAT DOES GENDER IDENTITY AND EXPRESSION MEAN?
Gender identity is one’s internal, personal sense of being a man or a woman (or a boy or a girl). For transgender people, their birth-assigned sex and their own internal sense
of gender identity do not match.
Gender expression is the external manifestation of one’s gender identity, usually expressed through “masculine,” “feminine” or gender-variant behavior, clothing, haircut, voice or body characteristics. Typically, transgender people seek to make their gender expression match their gender identity, rather than their birth-assigned sex.
Gender identity and sexual orientation are not the same. Transgender people may be straight, lesbian, gay or bisexual. For example, a man who transitions from male to female and is attracted to other women would be identified as a lesbian or a gay woman.
-GLAAD Media Reference Guide, 8th edition