Bi Visibility Day began in 1999 and every year, on 23 September, members of the bi community take part in events to increase awareness and understanding of bisexuality. Like this actor: "Look at me! I'm visible!"
The idea for the day came from three bisexual activists in the US: Wendy Curry, Michael Page and Gigi Raven Wilbur. Wilbur explained:
Ever since the Stonewall rebellion, the gay and lesbian community has grown in strength and visibility. The bisexual community also has grown in strength but in many ways we are still invisible. I too have been conditioned by society to automatically label a couple walking hand in hand as either straight or gay, depending upon the perceived gender of each person.
Individuals take part, but also groups like Stonewall, the LGBT rights organisation: "Some people are bi. Get over it."
Bisexual celebrities like Evan Rachel Wood, have also got involved.
Wood summed up the sentiment behind the day: "Bisexual people are the largest single group within the LGBT community, yet we are hardly recognised."
The actor explained her own experiences of biphobia and bi invisibilty.
Other bi people showed their support for #BiVisibilityDay in different ways. Some simply matched their lipstick to the colours of the bisexual flag.
Some took the more traditional route and waved the flag. "Flying it proudly."
This academic and feminist writer from the University of Sussex simply waved to show her support:
Students wrote about the subject, too. "I actually just wrote a paper about being bi and invisible."
This young Scottish guy held up a sign saying why he thinks the day is important: "#BiVisibility creates safe spaces lets people know they aren't alone."
This woman just said, "It's me!"
Some photos were not selfies but posted by people who wanted to remind others of bi people who are no longer with us, like the great Caribbean-American poet, June Jordan.
And other people just wanted to remind the world that they're here: "Some selfies bc it's #BiVisibilityDay and I exist."
Or to remind people of kick-ass bi TV characters, like Dr Callie Torres from Grey's Anatomy.
It was also a time to show thanks for support from friends and family: "It's great to be accepted by the ones you love and love you."
Others used the day the encourage fellow bi people to come out: "I hope you feel safe enough to join me one day."
There were messages for heterosexuals, like this one directed at a certain kind of straight person: "I'm not just your gateway into a threesome."
Some people just took a selfie and tweeted the hashtag.
But lots of people wanted to be more direct. "My sexuality is valid and if you don't think so you can fuck off."
Or to celebrate being bi while making a joke about the normally low levels of visibility. "Rejoice the 1 day of the yr we are visible before we retreat to our subterranean mole lairs!"
It has been a proud day for bi geeks. "Happy #BiVisibilityDay from this huge bisexual dork (me)."
As well as reminding the universe that black, bisexual men exist too. "I'm proud of it!" #YesWeExist
And for being bi, proud and spreading the message while chilling out. "Happy #BiVisibilityDay from this bisexual who's mostly spending their day in bed."
Others took to the streets in their selfie. "I'm my own Bi #PrideHeroes #BiVisibilityDay."
This button summed up the day, revealing what many were saying about how bi people are so often erased from sight.
BuzzFeed News asked all those included in this story for permission to use their posts.
Patrick Strudwick is a LGBT editor for BuzzFeed News and is based in London.
Contact Patrick Strudwick at firstname.lastname@example.org.
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