LGBT is an initialism that stands for lesbian, gay, bisexual, and transgender. In use since the 1990s, the initialism, as well as some of its common variants, functions as an umbrella term for sexuality and gender identity.
It may refer to anyone who is non-heterosexual or non-cisgender, instead of exclusively to people who are lesbian, gay, bisexual, or transgender. To recognize this inclusion, a popular variant, LGBTQ, adds the letter Q for those who identify as queer or are questioning their sexual or gender identity.