Heteronormativity is the assumption that everyone is heterosexual, or that being heterosexual is the only "normal" sexual orientation. Heteronormative social systems incentivize conforming to the behavior and appearance of heterosexuality. Heteronormativity can manifest as heterosexism, the biased belief that heterosexual identity is the only valid sexual orientation. Individuals, communities, policies, and institutions can perpetuate heteronormativity and heterosexism, and thus marginalize queer people and communities.