Bartering
Also known as: barter deal
Bartering is a form of doing business where no money is paid for a product or service, but a service is rendered in return. Bartering is thus a kind of barter deal. Bartering deals occasionally happen in the (online) marketing world. In exchange for advertising space or airtime, products are offered to the publisher of the website or other medium.
Marketing through contests/competitions is also classified under bartering.