Collection: Square

Definition: "Filed straight across the top, with flawless 90 degree angle sides," says Miss Pop. "I always associate this shape with nail queens Gwen Stefani, Missy Elliot, and Dolly Parton. It’s their go-to file. I’d also add that this shape is very popular on the West Coast."

Bottom Line: If you have narrow nail beds and slim fingers, this is the perfect shape for you. "I classify it as a modern shape and it seems to have appeal among younger people," says Choi.