Choosing yours
More than any additional tool, a ratchet can last you a lifetime. Quality ratchets could be serviced inexpensively and so should never degrade. Sockets happen to be interchangeable because they’re all standard. Buy the very best ratchet you can afford, even if you buy inexpensive sockets to start with.
Socket release
Sockets are held onto the ratchet by using a bit of spring-loaded ball privately of the square drive. After applying a lot of push, I’ve frequently found sockets get trapped on the travel and the only path to have them off is usually to hammer the ratchet on the floor or even hold it in a vice. Good quality ratchets include a button on the trunk which efficiently pushes off the socket when you are ready to Ratchets Wheel release it.
1/4 inches – Used for smaller sockets and precision work. Valuable for dismantling individual components on the bench.
3/8 inch – The middle sized, and for me, most useful size for standard use on an automobile. A 3/8″ drive can travel sockets of all sizes. It is big enough to use a great deal of force, but certainly not too big to match into tight spaces
1/2 in . – 1/2″ sockets are usually used for nuts and bolts from around 10mm or more. A 1/2″ drive socket can apply enough pressure to undo all nuts on an automobile.
There are also 3/4″ and 1″ ratchets but these are being used on trucks, tanks and commercial machinery.
Tooth count
Inside a ratchet 
there is a toothed wheel which allows it freely rotate as you tighten the nut. Each just click you hear is a tooth moving the ratchet. The more tooth there are, the significantly less movement is necessary on the gain stroke. A ratchet with 75 teeth will work considerably faster than a 32-tooth ratchet. Making high tooth-counts requires quality engineering and developing, so as an over-all 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 3 sizes of drive. Everywhere in the globe these sizes are given in inches – even when the sockets happen to be metric.