Gender identity is the personal sense of one's own gender. Gender identity can correspond to a person's assigned sex or can differ from it. In most individuals, the various biological determinants of sex are congruent and consistent with the individual's gender identity. Gender expression typically reflects a person's gender identity, but this is not always the case. While a person may express behaviors, attitudes, and appearances consistent with a particular gender role, such expression may not necessarily reflect their gender identity. The term gender identity was coined by psychiatry professor Robert J. Stoller in 1964 and popularized by psychologist John Money.
In most societies, there is a basic division between gender attributes associated with males and females, a gender binary to which most people adhere and which includes expectations of masculinity and femininity in all aspects of sex and gender: biological sex, gender identity, gender expression, and sexual orientation. Some people do not identify with some, or all, of the aspects of gender associated with their biological sex; some of those people are transgender, non-binary, or genderqueer. Some societies have third gender categories.
