Vendors engage the services of affiliates to do marketing of the product on their behalf. But how do vendors and affiliates meet? Well, vendors can engage affiliates directly to sell their products and services. Another option is for vendors to join affiliate networks. These are companies whose sole purpose is to serve as the meeting place for vendors and affiliates. The advantage of an affiliate network is that a vendor can find thousands of relevant affiliates there without having to run around looking for them all over the internet.