How Search Engines Work

Search Engine Optimization is the art of taking a website and helping search engines, such as Google, realize the importance and relevance of the site for specific search terms. Search engines utilize automated software to find, read, record, rank and return web pages.

Let’s see how search engines work so we can better understand optimization:

  • Find – A search engine can’t return any results if it doesn’t know what’s out there on the web. Search engines use software that crawls the web looking for new pages by following links from known pages or by visiting pages that were submitted directly to the search engine. It is important to have a good internal linking structure on your site and to submit sitemaps to the search engines so that all of your pages will be found.
  • Read – Once a search engine finds a page it attempts to read it. A web crawler can read any text or HTML code on a page, but it cannot read any images, audio or video. For this reason it is important to avoid using images with text in them or building your entire site using Flash.
  • Record – Once a search engine has read a web page, it decides whether or not to record, or index, the information it has discovered. Typically, the search engine will keep a record of all the content on the page and will come back and update the information the next time the web crawler comes along. Sometimes only the URL is recorded or the page is not indexed at all.
  • Rank – Ranking is what makes a search engine useful. The search engines use software that is designed to evaluate web pages much like a human would. Since computers don’t really work like humans, the software uses algorithms to evaluate key factors that indicate the relevance, importance and popularity of a web page. For example, the software reads the page title, which is located the HTML title tag in the page’s source code, and checks to see if the keywords you are searching for are in it. If so, this is a strong indicator that the page is relevant for your search terms. The software also looks at incoming links as ‘votes’ for a web page, so the more links a page has the more likely it is to have important information that would be useful.
  • Return – This is the last stage of the process where you actually see the list of web pages related to the search terms you entered. Believe it or not, just because your web site normally ranks on the first page for a specific term, it doesn’t mean that it will always be returned on the first page. There are many factors that determine what pages appear first, including the location of the computer the search was performed on, which data center the request ran through, and whether the user was logged in.