There are prefolds, which are just the flat, "old-time" diapers (not to be confused with "flats" which you have to fold a few times in order to create the thickness).
You either pin them or use a plastic Snappi to hold it on. Or, some diaper covers are made so that they will hold the diaper in place without having to use a separate pinning mechanism. In the summer, my babies just wear a pre-fold without a cover.
The pros are that they are cheaper and a lot less trouble to maintain. You don't have to worry about stuffing them (like with the pocket diapers). You can just wash them, dry them and throw them in a pile until you need them.
Then there are fitted diapers, which are like disposable diapers in their shape and in the way you put them on. They have elastic around the legs and either close with Velcro or snaps. You have to use a cover with these as well.
The Pros are that you don't have to worry about pinning them and you just put them on like a disposable.
The pros are that these are probably the most convenient as you literally use them just like disposables. You don't have to worry about stuffing them (as with the pocket diapers), you don't have to worry about a cover, you don't have to worry about pinning.
The cons are that they can be bulky and that if you have a heavy wetter they can leak. They are also pretty expensive. Depending upon how many layers are sewn into the diaper, they can take a long time to dry.
Last are the Pocket Diapers. They are "All-in-ones" in that they have the waterproof cover already sewn on. The difference is that you stuff these with 'inserts' (which can be anything from a pre-made insert to a folded up flat diaper).
The pros are that you can stuff them with as little or as much "stuffing" as your child needs (or as the situation calls for, stuff it heavier for long car rides, lighter for around the house). They also, for some reason, tend to be more trim and not as bulky as some of the others.
The Pocket Diapers were my favorite with my now four year old. But I got so that I literally dreaded getting them out of the dryer and having to stuff them all. That's why I switched to the pre-folds....they were so much easier. I am also concerned with using synthetic fabrics...I much prefer natural fibers. With Zoe I use unbleached prefolds with wool covers.
I also had times when I used the cloth at home and disposables at night and when we went out. Every little bit helps with finances and with the environment. It doesn't have to be "all or none".
Within the four basic style of diapers you will find different features and different materials. It can get pretty overwhelming. You just have to break it down in your mind. Categorize it into one of the categories and then go from there.
With all types, you will find a few "store made" brands and then tons of WAHM (work-at-home-mom) brands.
Then there are the covers. That opens a whole new Pandora's Box. The basic two, though, are wool versus synthetic waterproof materials.
I much prefer wool. Wool can store moisture up to 35 per cent of its own dry weight yet it remains dry to touch and speeds up the body's own cooling system. Wool is breathable, it doesn't hold in the heat like plastics would. It allows for the circulation of air. This helps to prevent diaper rash. Wool contains natural lanolin which creates a natural waterproof barrier. Wool is also an anti-bacterial. It does not have to be washed between every diaper change. Once every few weeks should be sufficient. Just let dry between uses.
You could also use a cover made with PUL. Some people find these to be less intimidating than wool...although, once you get the hang of wool, it really is quite simple.
There are many places online where you can buy and/or trade for new and used cloth diapers. Unfortunately, ebay has prohibited the selling of used cloth diapers at this time. There is a petition circulating to try to get this rule amended but in the meantime you will have to look elsewhere. Some of the sites where I have found mine are http://www.diaperswappers.com/ and http://www.mothering.com/ as well as http://www.amitymama.com/. You can also do a google search on the type of diaper you are looking for and find tons of sites.