Working with a network of aligned sites to drive traffic and ultimately sales back to a brand/retailer/advertiser. The affiliate typically earns a commission for the sales they drive from the referred traffic.
Example: A fashion retailer has a bag featured on an editorial sites ‘Top 20 bags for Autumn article. A customer reads the article, clicks on the link and goes on to purchase a bag. The editorial site is joined to the fashion retailer’s affiliate programme so they earn a commission for the sale generated from their referral.
Reference: Affiliate Marketing beginners guide