SEO Basics - Search Engines

 

The three main components of a search engine that will affect search results are:

• The Webcrawler (spider)
• The Database
• The Search Algorithm

 

Webcrawlers literally search through pages on the internet. They begin with one page and follow links to other pages. If your page is not linked to from another website, it is likely that it will not be found by search engines.

 

Crawlers are scheduled to crawl pages and documents at various intervals. When a website updates its content often, it invites the spider to crawl more frequently. The purpose of spiders is to keep fresh content in the search engine database.

 

All of the information retrieved by the spiders is stored in the search engine database. Hence, the database is what you are actually searching, not the live web. Search engines sort web pages by words. Words that stand out in headers or that are set apart from normal text may be given additional weight by search engines.

 

The search algorithm ranks the most relevant documents first. All search engine algorithms evaluate the location and frequency of keywords on a page. Following keyword relevancy, the algorithm places weight on the quality and ranking of web pages linking to the page. Some search engine algorithms also monitor click-through data with search queries to enhance user acceptance. This means that if a page is not attracting clicks or the user clicks back quickly, the search engine will demote that high-ranking page and promote a lower-ranking page that does attract and keep visitors.

 

As algorithms are constantly being updated, it is not uncommon to see changes in rankings from time to time. Search engines constantly update and refine their ranking algorithms in order to index the most relevant websites.  Make sure that your SEO consultant is maintaining your Web site with fresh content and new links. 

 

Written by Nicole Timofeyeva
January 1, 2008