There are networks which have integrated more affiliate programs under one affiliate management service. When you signup for such network you can choose from many companies offering different products and commisions.
For those companies it is easy way how to get new customers and they dont have to worry about marketing. It is Affiliate network job and its publishers to put companies banners on their websites.

Usualy there differeret program types, most common is CPA (cost per action) or CPS (cost per sale) or CPC (cost per click) sometimes CPC and other programs.

In this toppic you can talk about such networks. The most common is Commission Junction (CJ), ShareaSale, ClickBooth and others.
Feel free to share your experince in this forum.

And do not put any Affiliate links in this topic.... Only place for affiliate links is your SIG.