Queer theory examines non-normative expressions of gender and sexuality. It rejects the idea that identities fit into fixed categories like male/female or gay/straight. Key theorists include Judith Butler, who argued that gender and other identities are fluid and performed rather than expressing an inner essence. Queer theory looks at ambiguity and fluidity in representations, describing spaces outside of binary categories as "queer spaces." It also defines "queer texts" as those dealing with queer themes or allowing queer readings that identify subtext.