In Internet marketing, search engine marketing, or SEM, is a set of marketing methods to increase the visibility of a website in search engine results pages (SERPs). The three main methods of SEM are:
Search engine optimization attempts to improve rankings for relevant keywords in search results by improving a web site’s structure, content, and relevant backlink count.
Pay per click advertising uses sponsored search engine listings to drive traffic to a web site. The advertiser bids for search terms, and the search engine ranks ads based on a competitive auction as well as other factors.
Paid inclusion can provide a guarantee that the website is included in the search engine’s natural listings. However, as of 2006 the leading search engine, Google, does not offer this service.