Affiliate marketing is also called "performance marketing", in reference to how sales employees are typically being compensated. Such employees are typically paid a commission for each sale they close, and sometimes are paid performance incentives for exceeding objectives. Affiliates are not employed by the advertiser whose products or services they promote, but the compensation models applied to affiliate marketing are very similar to the ones used for people in the advertisers' internal sales department.
There are two ways to approach affiliate marketing: You can offer an affiliate program to others or you can sign up to be another business's affiliate. As the business driving an affiliate program, you'll pay your affiliates a commission fee for every lead or sale they drive to your website. Your main goal should be to find affiliates who'll reach untapped markets. For example, a company with an e-zine may make a good affiliate because its subscribers are hungry for resources. So introducing your offer through a "trusted" company can grab the attention of prospects you might not have otherwise reached.