Ab crack is the newly-coined term by Elle for an unrealistic trend you can love to hate on Instagram. It refers to having a visible line or split right down the middle of your stomach (the line that vertically splits a six pack of abs). It's only really practical to achieve if you're already naturally super slim, and follow that up by working out like a crazy person to get super cut. Much like thigh gaps and other impossible beauty standards, ab crack is a trend that's only possible if you're a professional model or fitness guru.

Sources: Elle