An ally or straight ally is a cisgender, heterosexual/romantic, allosexual/romantic (cishet) individual who is not a part of the LGBTA+ community but supports the community. An ally acknowledges that LGBT people face discrimination and thus are socially disadvantaged, supports LGBT+ rights, and challenges homophobia, transphobia, etc. Not everyone who meets this definition identifies specifically as an "ally". Not all cishet people are allies.
It is unknown when the term "ally" was first used, however it has been around seemingly since the post events of The Stonewall Riots.
The straight ally flag was created sometime in the late 2000s, but the specific origin is unknown. The cisgender ally flag was created by Twitter user @vaultausir at an unknown time.
The polyamorous ally flag was created by William on January 21, 2021, as she noticed the lack of polyamorous support amongst many polyamorous people.
The PoC/tPoC ally flag was also created by William, in order for white cishets to show support to not only transgender and queer people, but support to POC and the struggles they go through. It was coined on January 22nd, 2021.
The xenogender ally flag was created January 8th, 2021, by wiki user ringotheman. It was made for non-xenic/non-xenogender people to show support for xenogender, xeno-aligned and xenic folks.
The old intersex ally flag was made by an unknown person, although it bothered The Chain Collective, who are bodily intersex, due to it implying that all intersex people were gay. The first alternative one was made by Rosie, at their request.