Gender identity is one's personal experience of one's own gender. All societies have a set of gender categories that can serve as the basis of the formation of a person's social identity in relation to other members of society. In most societies, there is a basic division between gender attributes assigned to males and females, a gender binary to which most people adhere and which enforces conformance to ideals of masculinity and femininity in all aspects of sex and gender: biological sex, gender identity, and gender expression. In all societies, some individuals do not identify with some (or all) of the aspects of gender that are assigned to their biological sex; some of those individuals are transgender or genderqueer. Some societies have third gender categories.