By definition: Essentially, it's when the fabric of a garment is cut at a diagonal angle. This technique takes advantage of the greater stretch in the bias, which in turn, accentuates body lines and curves, and allows for the fabric to drape softly.
Why it matters: The bias-cut is extremely form-flattering when executed well. Case in point — Pippa Middleton's legendary silky bias-cut Alexander McQueen gown, worn at the Royal Wedding. The dress draped in all the right places, darted in at the knees to better highlight her toned curves, and showcased her, um, best asset.