The steering axis is a line drawn through the upper and lower ball joints of the knuckle. Positive caster is when the bottom of the steering axis line is in front of the tire's contact patch. Zero caster is when the steering axis is at 0o. Too much positive caster causes hard steering, excessive road shock and shimmy. Camber is the inward or outward tilt of the front tires as viewed from the front.
Inward tilt is negative, outward tilt is positive.
Camber is used to distribute load across the entire tread. Improper camber makes the tire wear on one edge, and causes the vehicle to pull to the side that has the most positive camber. If the distance is closer at the front, it's called toe-in. If the difference is closer at the rear, it's called toe-out. Some suppliers suggest that they have reinvented the wheel.