Where does come from?
First, some history:
The female sign goes back to at least 5 BCE, used by Greek astrologers and alchemists to represent Venus (the planet and goddess of love). In the mid-1700s, Swedish naturalist Carl Linnaeus—the guy who gave us all those Latin names in science, or binomial nomenclature—had the idea to use the female sign to mark the female sex in plant genetics. That convention spread to medicine and other fields, notably adopted by feminists in the 1970s.
The female sign emoji was approved by Unicode in 1993, becoming widespread under Unicode 6.0 in 2010. On several platforms such as Twitter, the emoji shows the female sign in white on a—yup—pink background. Since 2010, Unicode has been offering female versions of emoji people whose defaults were, of course, men (e.g., female and male firefighters).
On older devices that don't support the upgrades, the female sign emoji may appear next to the generic forms to indicate "woman," (e.g., the merperson emoji plus the female sign emoji may pop up on screens that can't show the mermaid emoji.
Who uses ?
Very often online, the female sign emoji simply displays after another emoji character because the full-fledged woman emoji isn't supported on the platform. In some instances, this may appear redundant because the default emoji person is already a woman.
On Twitter, for example, it's very common to see the female sign emoji after the person facepalming, person raising hand, person shrugging, or person gesturing no emoji, as actress Gal Godot did when tweeting about her Wonder Woman role:
Thank you @MTV for nominating Wonder Woman for Best Movie, Best Hero, and Best Fight! We are so grateful for all the love the film continues to receive and so so excited for what we are planning for you guys in WW's next adventure.. 💃🏻🙅🏻♀️🙏 #wonderwoman pic.twitter.com/WgnddOqrca
— Gal Gadot (@GalGadot) May 3, 2018
When used alone, the female sign emoji may mark content expressing feminine pride and feminist solidarity, notably used in the January, 2017 Women's Marches around the world and in the wake of the #MeToo movement exposing sexual violence and assault against women.
Great to catch up with my federal parliamentary sisters in #Perth 🙋♀[...]
@JulieBishopMP, April, 2018
Loving how many female athletes are up for @BBCSport SPOTY. It's not positive discrimination, it's equality-all outstanding achievers♀👏🏅
@runlikeforrest, November, 2016
shout out to all the women who participated in the Women's March ♀💓
@jaylaaaxo, January, 2018