What are "cobranding" and "affiliate programs" and do I need a written agreement?

Cobranding refers to a relationship between parties where one or both parties “brand” or in some way promote the other party on its website. It most often refers to situations where one party’s website, the cobranded party, is visible from within the website of another party, the cobrander. Users of the cobrander website see the top or side frame of the cobrander site and a page from the cobranded website within it. The cobranded site can reside on the server of either party, but usually it remains on the cobranded party’s server.

Cobranding is different than an affiliate program which typically involve only banners or links to another party’s sites. Otherwise, both agreements may have similar provisions including how cross promotion will occur, a cross trademark license, that each party is responsible for its own site, how sales will be tracked, which sales are included and how payments will be made.