Queer is an umbrella term used by members of the LGBTQIA+ community to refer to any identities that are not heterosexual or cisgender. Many people use queer to describe themselves as non-cisgender or non-heterosexual when specifics aren’t required. The term also has utility as a way to indicate that sexual orientation and gender identification can be fluid or impossible to describe in a single label.
Historically, “queer” was used as a synonym for weird or strange, but later found use as a slur for gay and lesbian people. Eventually, through the efforts of LGBTQIA+ activists and allies, the word “queer” was reclaimed and transformed into an umbrella term to be used to describe the community. The choice to keep a previously harmful word like queer in the modern LGBTQIA+ lexicon is representatitive of the turbulent history of sexual minorities in hetero/cisnormative environments.