These are folds of fabric that are stitched to a point. They are used to add shape to a garment skirt or bodice so that it fits the curves and contours of the body. They are most common at the waistline or bust.
Plain or single point darts
Darts shaped on the pattern like a V.
Contour or double point darts
A long dart which is widest and fits at the waistline and then tapers to points at both ends to shape the bust and the hips.
Darts that extend diagonally from the side seam in the hip area to the bust. The diagonal can be straight or slightly curved.
Click on the links below for more information about darts:
Sewing the continuous thread dart (tutorial)