Time for an anatomy lesson: The puborectalis (a u-shaped muscle that wraps around the rectum) is one of the bodily functions that stops you from pooping yourself. When you're sitting at a 90-degree angle — as one does on a Western-style toilet — the puborectalis is still in a position that restricts the poo pathway. On the other hand, squat toilets (which are common in some Asian and Middle Eastern countries) put you in the best position to get your bowels moving, as you squat over the toilet in a position that relaxes the puborectalis.
The Squatty Potty allows you to replicate the experience of a squat toilet on a Western-style toilet. Pooping with the stool beneath your feet helps you position your body so that the puborectalis loosens its hold on the rectum and allows the rectal passageway to relax and open.
Read BuzzFeed's full guide on the Squatty Potty for more details!