Correct wheel alignment is essential for safety, fuel economy and tyre wear reasons. For a high performance or track car these reasons translate to mean good road holding and optimum performance.
The most basic alignment setting that most people have heard of is tracking. This is the relationship between the two (front or rear) wheels, when looking from the top of the car. If the front of the wheels point inwards, this is called toe-in, outwards is called toe-out.
There are a number of other suspension alignment settings on all four wheels which we would check in a full alignment service, as the manufacturers will have specifications for these. If they are found to be out of specification, but there is no adjustment available, this would indicate that there is damage to that area of the suspension, and further investigation would be required to find the cause.
On a full four-wheel suspension geometry alignment service we would check and adjust (where possible) the tracking (as described above), the camber (which is the relationship between the road and the wheel), and the caster (how the camber changes during steering) of the front wheels. The tracking and camber of the rear wheels. Plus the relationship between all four wheels as it would be possible for example for the rear wheel alignment to cause the car not to run straight (often called 'crabbing').