Identity is the qualities, beliefs, personality traits, appearance, and/or expressions that characterize a person or group.

In sociology, emphasis is placed on collective identity, in which an individual's identity is strongly associated with role-behavior or the collection of group memberships that define them. According to Peter Burke, "Identities tell us who we are and they announce to others who we are." Identities subsequently guide behavior, leading "fathers" to behave like "fathers" and "nurses" to act like "nurses."

In psychology, the term "identity" is most commonly used to describe personal identity, or the distinctive qualities or traits that make an individual unique. Identities are strongly associated with self-concept, self-image (one's mental model of oneself), self-esteem, and individuality. Individuals' identities are situated, but also contextual, situationally adaptive and changing. Despite their fluid character, identities often feel as if they are stable ubiquitous categories defining an individual, because of their grounding in the sense of personal identity (the sense of being a continuous and persistent self).