Even if you haven't heard of a 'belfie', chances are you've probably seen one.
Many of us have managed to perfect the art of the regular selfie (if you're still unsure of just how to showcase your mug in its best light, check out Kim K's tips here) - but how on earth do you present your butt to the world at its most flattering angle?
Fitness fanatic Jen Selter has managed to accrue over 1.3 million Instagram followers, mostly by focusing on her best ASSet (sorry, I couldn't help it).
After noticing that fitness was a big thing on Instagram she decided to create her own account where she posted snaps of random people working out as well as inspirational quotes to motivate her followers.
But she soon discovered the key to amassing a legion of fans was posting pictures of herself, pictures of her yoga-pantsed derriere from behind to be more specific.
In an interview with Elle.com, Jen Selter said each time she posts a butt shot, she gains four to five thousand new Instagram followers, and she's not a singular phenomenon.
Semi-anonymous physique models (almost always women) have become as integral to Instagram as shots of fashion bloggers and beautiful sunsets.
Who could forget the infamous Facebook 'She squats, bro' page whose slogan now appears on singlets worn by countless gym-goers all over the world. It seems exercise-honed bottoms are something of an obsession on social media.
According to Selter, those showcasing their own bodies are often in it to inspire others and motivate them toward a healthier way of living - although getting their impressive bodues out there and becoming sought after models isn't a bad perk.
Due to her serious following, Selter has been overwhelmed with sponsorship and 'shout out' offers including opportunities from high profile sports labels such as Nike, Lululemon and New Balance.
Though she declined to reveal exact figures, Selter told Elle.com she can make thousands for a simple selfie by the barbells. Money is far from her sole concern, though.
"When I see someone advertising for 100 different companies, it's like, Okay, this person is just in it for making money," she said. For her, "It's more of a passion."
The idea of belfies certainly has its critics, after all people are more likely to know Selter by her butt rather than any other part of her - surely that's objectification at its very worst?
But Selter is evidently empowered and proud of her body, and if she can get other females on her fitness wavelength, then more power to her.
Check out a selection of belfies from Jen Selter's Instagram below:
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