Affiliate marketing has grown quickly since its inception. The e-commerce website, viewed as a marketing toy in the early days of the web, became an integrated part of the overall business plan and in some cases grew to a bigger business than the existing offline business. According to one report, total sales generated through affiliate networks in 2006 was £2.16 billion in the UK alone. The estimates were £1.35 billion in sales in 2005. MarketingSherpa’s research team estimated that, in 2006, affiliates worldwide earned $6.5 billion in bounty and commissions from a variety of sources in retail, personal finance, gaming and gambling, travel, telecom, education, publishing and forms of lead generation other than contextual ad networks such as Google AdSense.

Currently the most active sectors for affiliate marketing are the adult, gambling and retail sectors. The three sectors expected to experience the greatest growth are the mobile phone, finance and travel sectors. Hot on the heels of these are the entertainment (particularly gaming) and internet-related services (particularly broadband) sectors. Also several of the affiliate solution providers expect to see increased interest from B2B marketers and advertisers in using affiliate marketing as part of their mix. Of course, this is constantly subject to change.