Affiliate marketing involves retailers rewarding affiliates for referrals that result in sales. The retailer only pays affiliates a commission after a sale is made through their referral. This allows affiliates to promote brands for free in the hopes of earning a commission. Setting up an effective affiliate program requires choosing an affiliate platform, providing product data feeds and banners, and dedicating resources to communication and engagement with affiliates to optimize efforts and increase sales over the long term. Regular testing of promotions and recruitment of new affiliates helps improve program performance goals over time.