Transgender is a category of gender identity, referring to a person whose gender differs from the one assigned at birth (usually assigned based on physical sex). For example, a person could be physically female, and thus assigned the female gender at birth (FAAB), and have a male gender, or vice versa. Genderqueer people sometimes also consider themselves to be transgender.
Transgender people may seek to take hormones to transition their sex toward their gender, and may undergo sex reassignment surgery. Previously, they were then known as transsexual, but this term is now considered offensive by many.