From the advertiser perspective

[edit] Pros and cons
Merchants like affiliate marketing,[17] because in most cases, it is a "pay for performance model", meaning the merchant does not incur a marketing expense unless results are realized, excluding the initial setup and development of the program. Some businesses owe much of their growth and success to this marketing technique, one example being Amazon.com, especially small and midsize businesses. However, unlike display advertising, affiliate marketing is not easily scalable.

[edit] Implementation options
Some merchants run their own affiliate programs (In House) while others use third party services provided by intermediaries to track traffic or sales that are referred from affiliates. (see outsourced program management) Merchants can choose from two different types of affiliate management solutions, standalone software or hosted services typically called affiliate networks.

[edit] Affiliate management and program management outsourcing
Main article: Affiliate manager
Successful affiliate programs require a lot of maintenance and work. The number of affiliate programs just a few years back was much smaller than it is today. Having an affiliate program that is successful is not as easy anymore. The days when programs could generate considerable revenue for the merchant even if they were poorly or not at all managed ("auto-drive") is over.
Those uncontrolled programs were one of the reasons why some of the not so positive examples of affiliates were able to do what they did (spamming,[18] trademark infringement, false advertising, "cookie cutting", typosquatting[19] etc.)
The increase of number of internet businesses in combination with the increased number of people that trust the current technology enough to do shopping and business online caused and still causes a further maturing of affiliate marketing. The opportunities to generate considerable amount of profit in combination with a much more crowded marketplace filled with about equal quality and sized competitors made it harder for merchants to get noticed, but at the same time the rewards if you get noticed much larger.
Recently, the internet advertising industry has become more advanced. Online media has in some areas been rising to the sophistication of offline media, in which advertising has been largely professional and competitive for many years already. The requirements to be successful are much higher than they were in the past. Those requirements are becoming often too much of a burden for the merchant to do it successfully in-house. More and more merchants are looking for alternative options which they find in relatively new outsourced (affiliate) program management or OPM companies that were often founded by veteran affiliate managers and network program managers.[20]
The OPM are doing this highly specialized job of affiliate program management for the merchant as a service agency very much like Ad agencies are doing the job to promote a brand or product in the offline world today.

[edit] Types of affiliate websites

Companies and websites in affiliate marketing
Affiliate sites are often categorized by merchants (advertisers) and affiliate networks. The main categories are:
Search affiliates that utilize pay per click search engines to promote the advertisers offers (search arbitrage)
Comparison shopping sites and directories
Loyalty sites, typically characterized by providing a reward system for purchases via points back, cash back or charitable donations
Coupon and rebate sites that focus on sales promotions
Content and niche sites, including product review sites
Personal websites (these type of sites were the reason for the birth of affiliate marketing, but are today almost reduced to complete irrelevance compared to the other types of affiliate sites)
Blogs and RSS feeds
Email list affiliates (owners of large opt-in email list(s))
Registration path affiliates that include offers from other companies during a registration process on their own website.
Shopping directories that list merchants by categories without providing coupons, price comparison and other features based on information that frequently change and require ongoing updates.
CPA networks are top tier affiliates that expose offers from advertiser they are affiliated with to their own network of affiliates (not to confuse with 2nd tier)

[edit] Publisher recruitment
Affiliate networks that have already a number of advertisers usually also have a large number of publishers already. This large pool of affiliates could be recruited or they might even apply to the program by themselves.
Relevant sites that attract the same audiences as the advertiser is trying to attract, but are not competing with the advertiser are potential affiliate partners as well. Even vendors or the existing customers could be recruited as affiliate, if it makes sense and is not violating any legal restrictions or regulations.
Almost any website could be recruited as affiliate publisher although high traffic websites are more likely interested in (for them) low risk CPM or medium risk CPC deals rather than high risk CPA or revenue share deals.[21]

[edit] Affiliate program detection
Affiliate programs directories are one way to find affiliate programs, another method is large affiliate networks that provide the platform for dozens or even hundreds of advertisers. The third option is to check the target website itself for a reference to their affiliate program. Websites, which offer an affiliate program often, have a link titled "affiliate program", "affiliates", "referral program" or "webmasters" somewhere on their website, usually in the footer or "About" section of the site.
Even if all those methods seem to indicate that a site does not have an affiliate program, could it still be the case that there exists a non-public affiliate program. The only way to find out for sure, is to contact the site owner directly and ask.