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). SEM strategies include:

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. It is not limited to pure text content and includes optimization for images, video, documents (such as PDF ) and other forms of content.

Social media optimization promotes by placing ideas or content within online communities with the hope that they will spread virally. This includes the use of video on websites such as YouTube , social bookmarking sites such as Del.icio.us , community sites such as MySpace or news sites with emphasis on user votes for relevance on sites such as Digg.

Pay per click advertising uses paid ads on other web properties to drive traffic to a web site. The advertiser bids in an auction based maketplace for search terms to get his customized ads displayed to users on other web properties, which could be the service providers own website (such as a search engine) or websites of partners of the provider. Partner websites could be other search engines or any other website, which is usually referred to as content network.

Paid inclusion feeds listings into search engines, typically comparison shopping sites or general search engines. The advertiser pays for the inclusion of his web pages in the index of the service provider. Advertisers often have to pay a pay per click fee in addition to the inclusion fee. Some providers don't charge for the inclusion itself, but solely on a pay per click basis, which is not to be confused with classic pay per click advertising.

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