Say that you tell your friend, “I promise to be there for you.” Your statement isn’t so much about what’s going to happen in the future as it is you saying something that is designed to transform how your friend sees you in that moment. The promising itself is the action in this sentence, but it is a special kind of action that creates itself through your speech. It's just like saying "I do," during the marriage ceremony—saying the words is the action that makes the marriage real. Promising and saying "I do" are performative utterances in that they are both instances in which doing/saying something creates the reality of that something. In Gender Trouble, Judith Butler takes much the same approach to describing gender by claiming it is performative, rather than expressive. Gender is not something we are, but something we do.

Butler’s notion of gender as performative is rooted in several insights she derives from her examination of theory—the constructedness of sex, the constructedness of gender, and her notion that language, culture, prohibitions, and power are the shaping forces of identity, not some essence that is simply inside of us, waiting to be expressed through the wearing of a dress or the batting of eyelashes.