Groups that campaign for the rights of transgender, transvestite, transsexual, third gender and other gender variant peoples have been in existence since the mid-20th century, and have multiplied greatly in number since the 1990s. They may use a civil rights or minority rights political discourse, or may instead aim to challenge the very institution of gender. Their goals are varied, but include legal change, such as recognition in one's chosen sex on official documents; challenging discrimination in institutions such as prisons, housing, employment, health and education; and combating violence against transgender people.