Darts are a triangular fold of material stitched wide at one end and tapering to a point. Darts are used to give fullness, provide freedom for arm movement, to give elbow room, and to make transitions in size from one area to another.
A Double dart, usually found at the waistline, is diamond shaped with long point at each end. Although darts are used extensively in garments, there are darts in lots of other projects, too.
Watch the video to learn how to sew darts and apply them to your projects.