Originally posted by westcoaststyle
A coilover is a spring with an adjustable perch that goes over your strut. You change ride height by moving the spring perch up or down on the threaded base.
Good quality coilovers are Ground Control and Skunk 2. These just provide the base, perches, and springs. So with these you will also need to buy some good aftermarket shocks.
Coilovers like tein, bilstein, koni, penske, etc come with specially valved and shortened struts with a threaded body rather than a threaded sleve that goes over the strut, but are really expensive and probably overkill if youre not road racing.
Strut tower bars and tie bars just firm up the chassis of the car.
Sway bars reduce body roll by connecting the left and right suspension to eachother and the car's frame via a steel bar that flexes.
That should answer your question... In the future try rephrasing your search to get more results. This stuff has all been covered. 
that's what I was going to say anyway.
h: :chuckles: