Historic development

Affiliate marketing has grown quickly since its inception. The e-commerce website, viewed as a marketing toy in the early days of the Internet, 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, the total sales amount generated through affiliate networks in 2006 was £2.16 billion in the United Kingdom alone. The estimates were £1.35 billion in sales in 2005. MarketingSherpa's research team estimated that, in 2006, affiliates worldwide earned US$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 advertising programs such as Google AdSense

Currently the most active sectors for affiliate marketing are the adult, gambling, and retail industries. The three sectors expected to experience the greatest growth are the mobile phone, finance, and travel sectors. Soon after these sectors came the entertainment (particularly gaming) and Internet-related services (particularly broadband) sectors. Also several of the affiliate solution providers expect to see increased interest from business-to-business marketers and advertisers in using affiliate marketing as part of their mix.

Web 2.0

Websites and services based on Web 2.0 concepts—blogging and interactive online communities, for example—have impacted the affiliate marketing world as well. The new media allowed merchants to become closer to their affiliates and improved the communication between them.

New developments have made it more difficult for unscrupulous affiliates to make money. Emerging black sheep are detected and made known to the affiliate marketing community with much greater speed and efficiency.

Compensation methods Predominant compensation methods

Eighty percent of affiliate programs today use revenue sharing or cost per sale (CPS) as a compensation method, nineteen percent use cost per action (CPA), and the remaining programs use other methods such as cost per click (CPC) or cost per mille (CPM).

Diminished compensation methods

Within more mature markets, less than one percent of traditional affiliate marketing programs today use cost per click and cost per mille. However, these compensation methods are used heavily in display advertising and paid search.

Cost per mille requires only that the publisher make the advertising available on his website and display it to his visitors in order to receive a commission. Pay per click requires one additional step in the conversion process to generate revenue for the publisher: A visitor must not only be made aware of the advertisement, but must also click on the advertisement to visit the advertiser's website.

Cost per click was more common in the early days of affiliate marketing, but has diminished in use over time due to click fraud issues very similar to the click fraud issues modern search engines are facing today. Contextual advertising programs such as Google AdSense are not considered in the statistic pertaining to diminished use of cost per click, as it is uncertain if contextual advertising can be considered affiliate marketing.

While these models have diminished in mature e-commerce and online advertising markets they are still prevalent in some more nascent industries. China is one example where Affiliate Marketing does not overtly resemble the same model in the West. With many affiliates being paid a flat "Cost Per Day" with some networks offering Cost Per Click or CPM.