Cost per Click and Search engine Optimization Marketing is an advertising model used on search engines, advertising networks, and content websites, where advertisers must pay when a user actually clicks on an ad to visit the advertiser's website. Advertisers bid on keywords they believe their target market would type in the search bar when they are looking for a product or service. When a user types a keyword query matching the advertiser's keyword list, or views a page with relevant content, the advertiser's ad may be shown. These ads are called a "Sponsored link" or "sponsored ads" and appear next to, and sometimes, above the natural or organic results on search engine results pages, or anywhere a webmaster chooses on a content page. Cost Per Click advertising is a search engine optimization (SEO) marketing technique.

As a marketing strategy for increasing a site's relevance, SEO considers how search algorithms work and what people search for. SEO efforts may involve a site's coding, presentation, and structure, as well as fixing problems that could prevent search engine indexing programs from fully spidering a site. Other, more noticeable efforts may include adding unique content to a site, ensuring that content is easily indexed by search engine robots, and making the site more appealing to users. Search engines look for sites that employ these techniques and may remove their listings.

Cost per Click ads may also appear on content network websites. In this case, ad networks such as Google Adsense and Yahoo! Publisher Network attempt to provide ads that are relevant to the content of the page where they appear, and no search function is involved. While many companies exist in this space, Google AdWords, Yahoo! Search Marketing, and MSN adCenter are the largest network operators as of 2007. Eye tracking studies have shown that searchers scan a search results page from top to bottom and left to right (for left to right languages), looking for a relevant result. Placement at or near the top of the rankings therefore increases the number of searchers who will visit a site. However, more search engine referrals does not guarantee more sales. SEO is not necessarily an appropriate strategy for every website, and other Internet marketing strategies can be much more effective, depending on the site operator's goals.

We divided our Cost Per Click Marketing section to the next categories: