A search engine searches the web for information on relevant topics found on web sites. Searches on the internet are done using keywords. Search engines index keywords and the sites where they located them. For instance, if you search for the keyword vitamin, the search engine will return a list of sites that contain the word vitamin. Search engines sort through the endless data so searchers can find whatever it is they are searching for.

The search engine needs to find the information to be able to provide users with relevant results. This is done using what are called web robots or spiders. The search engine spiders always "crawl" pages looking for new content. After locating some information, it gets organized into a list. The spiders generally start the search for new information on popular sites. Then they follow each link on the site. The words on the website are indexed along with the links on the site to keep track of where they were found.

The spiders can work extremely fast, covering about 100 pages per second. Spiders crawl web pages from behind the scenes, from top to bottom, left to right, much like we read the page. Keywords close to the top of the page are given more weight. So are words in bold, title text, underline, italicized or highlight.

Spiders read the Meta tags, not just the text you can see. Meta Tags allow you to chose keywords to help in indexing your site.

After the information is located and indexed, it is organized for the use of searchers. Included in the index is the keyword or phrase, URL, and the number of times the keyword appears on the site. Giving searchers the most relevant result is the search engines job, so keyword density is important on the site.

The exact methodology used by the search engines is a highly guarded secret. It is important to understand some of the basics of how the search engines work in order to optimize your page for the search engines.

If you want to maximize the traffic you receive from search engines it is important to practice good SEO. There are many resources and information available like articles, eBooks and even free SEO courses.