. It will stay because it is one of the top marketing projects that human mind could ever think. It has many advantages to other marketing programs and is growing bigger and bigger all the time.
Affiliate Marketing has three types of promotion.
1) Promoting merchant's products with links or banners to your website/blog.
2) Promoting merchant's products from your own web store, constructed by your merchant.
3) Having affiliates to promote your products into their websites.
The first two types are pretty much the same. You don't have your own products, you don't pay to buy them and resell them, and you just get commission when somebody bus these products from your affiliate link or web store. You take advantage of your traffic in your web site, or you try to create traffic to your new web store. You spend some time and money for advertising and that's it.
Third type is kind of the opposite of first two. You have your own products and you "hire" affiliates in order to increase your chances of getting your products shown to the market. A commission is given whenever your products are being bought from their affiliate links or web stores.
There are no specific products used for affiliate marketing. There is a large variety of them, you can find almost anything to promote, but you must be careful of what to choose. Do a research and find what best fits you, and your audience.