Darts are folds sewn into fabric to provide three-dimensional shaping to a garment. They are very frequently used to tailor the garment to the wearer's shape.
Darts are actually a simple wedge shape, that is made up with four basic components:
Darts can be placed symmetrically on both sides of a garment or asymmetrically to allow for unique pattern design and creativity. Darts are sewn either tapered, or shaped.
There are several areas that common use a dart:
Have you seen FashionSewingBlogTV's video - Adjusting Darts for a Larger Tummy yet? Here it is:
Adjusting for a Larger Tummy