SEO is a form of online marketing. Search engine optimization (or search engine marketing) is the process of making a site and its content highly relevant for both search engines and searchers. Successful search marketing helps a site gain top positioning for relevant words and phrases.

There is much confusion about search engine optimization (SEO) and its relation to search engine spamming. Generally, legitimate search engine optimization adds to the user experience, while search engine spamming takes away from the user experience, although there is much gray area between the clear-cut examples on either side

Optimization involves making pages readable to search engines and emphasizing key topics related to your content. Basic optimization may involve nothing more than ensuring that a site does not unnecessarily become part of the invisible Web (the portion of the Web not accessible through Web search engines). Advanced optimization may include significant research into every element of page design, site structure, and off-the-page criteria.

Before pages can be optimized, research must be done to determine which keywords to target. This involves finding relevant keywords, determining their popularity, assessing the amount of competition, and deciding which keywords can be best supported with quality content.