Choosing yours
More than any various other tool, a Ratchets Wheel ratchet will last you a lifetime. Quality ratchets 
can be serviced inexpensively therefore should never wear out. Sockets are interchangeable because they are all standard. Buy the finest ratchet you can afford, even if you get inexpensive sockets to start with.
Socket release
Sockets will be held onto the ratchet by using a minor spring-loaded ball on the side of the square travel. After applying a lot of pressure, I’ve often found sockets get stuck on the drive and the only path to get them off is to hammer the ratchet on the floor or even hold it in a vice. Good quality ratchets add a button on the back which easily pushes off the socket when you are ready to release it.
1/4 inch – Used for smaller sockets and precision work. Beneficial for dismantling individual pieces on the bench.
3/8 inch – The center sized, and for me, most useful size for general use on a car. A 3/8″ travel can travel sockets of most sizes. It really is big enough to use quite a lot of force, but not too big to fit into tight spaces
1/2 inches – 1/2″ sockets are generally used for nuts and bolts from around 10mm and up. A 1/2″ travel socket can apply enough power to undo all nuts on a car.
Additionally, there are 3/4″ and 1″ ratchets but these are used on trucks, tanks and industrial machinery.
Tooth count
Inside a ratchet you will find a toothed wheel which allows it freely rotate as you tighten the nut. Each simply click you hear is normally a tooth moving the ratchet. The more tooth there are, the a lesser amount of movement is necessary on the returning stroke. A ratchet with 75 teeth will continue to work considerably faster than a 32-tooth ratchet. Making high tooth-counts requires top quality engineering and manufacturing, so as a general guide the better top quality tools will have a higher tooth count.
Drive sizes
socket-drive-sizes
All ratchets accept sockets by using a square travel and mostly there are three sizes of drive. All around the world these sizes are given in inches – even when the sockets are metric.