All three of these angles need to be properly set for alignment to be correct. Camber is the inward or outward tilt of a wheel compared to a vertical line. If the camber is out of adjustment, it will cause tire wear on one side of the tire's tread. Caster is the degree that the car's steering axis is tilted forward or backward from the vertical as viewed from the side of the car. If the caster is out of adjustment, it can cause problems in straight-line tracking.
Caster has little affect on tire wear.
Toe refers to the directions in which two wheels point relative to each other. Incorrect toe will cause rapid tire wear to both tires equally. Toe is always adjustable on the front wheels and is adjustable on the rear wheels of some cars. Before alignment, the technician should take your vehicle for a test drive to determine how it is out of alignment. The test drive should be done on a flat, straight road, a road with several bumps and dips, and a road that requires left and right turns.