TOS stands for Terms of Service. In the affiliate world, this most often refers to the program terms of an affiliate program. The terms of service – sometimes also referred to as Terms of Use – tells you what the rules of the affiliate program are and sets out what you can and can't do. For example: The TOS may prevent affiliates from bidding on the merchant's brand keywords. If you then bid on those brand keywords, you'd be violating the TOS of the affiliate program and would likely be kicked out as a result.

You should also make sure you aren't competing with your own affiliates for eyeballs. Any marketing channels you're using, such as search engines, content sites or e-mail lists, should be off limits to your affiliates. Put marketing restrictions into your affiliate agreement and notify partners immediately. It's your program--you set the rules. Or, if you prefer, you can let your affiliates run the majority of your internet marketing.
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