Search engine optimization (SEO) should not be confused with that of search engine marketing (SEM), that is. Other individuals in the industry use the two terms interchangeably nonetheless; they are not synonyms. They have their own sets of differences.

SEO refers to improving the natural and organic rankings of websites in the search engine results. It uses 2 main components for optimization - the on-page and the off-page. The former includes the use keywords in the content, original and relevant content, title tag optimization, site map, meta tags, and indexability of the website. Consequently, off-page optimization uses keywords in the anchor text, quality and relevancy of the links to the site, and amount of incoming links.

SEM, on the other hand, refers largely to text advertisements that usually appear on the right portion or at the top of search engine result page. They may come in the form of Adwords from Google or Overture from Yahoo. SEM also covers PPC search engine internet marketing, CTR marketing, and more. SEM creates great traffic for the site however; the conversion rate is debatable.