Heterosexuality is a sexual orientation characterized by romantic and sexual attraction or behavior between people of the opposite sex or gender. Heterosexual men are attracted to women, and heterosexual women are attracted to men. The prefix "hetero" comes from the Greek word "heteros," which means "the other (of two), another, different, second; other than usual". Heterosexuality is one of the three main categories of sexual orientation within the heterosexual-homosexual continuum, along with bisexuality and homosexuality. Most people across cultures are heterosexual, and heterosexual activity is the most common type of sexual activity.

Other terms related to sexual orientation include homosexual (same-sex attraction), bisexual (attraction to more than one sex), asexual (no sexual attraction to any sex), aromantic (no romantic attraction to any sex), and polysexual (attraction to people of various genders) . Despite the large number of individuals that identify as heterosexual, its important to respect any individuals sexual orientation and the label they choose.