Search Engine Optimization

How does search engine optimization work?

The Spider

Google has a tool called the Spider, which searches each Web site on the Internet. When it lands on a Web page, the Spider updates the information used to supply search results. This means that a Web site's optimization does not take full effect until the Spider tracks it. For example, a developer might optimize a Web site to include the keyword "apples". Perhaps the site did not previously show up in the search results for "apples". If the Google Spider lands on the Web site a week after optimization, it notices and logs the changes. If the SEO was successful, then the Web site will show up higher on the search results for "apples."

Google has its own scoring system for Web sites, called PageRank. This system, which assigns a score from zero to ten, represents a site's relative importance on the Web. A higher PageRank increases a site's priority of inclusion in search results. Although certain elements of PageRank determination are only known to Google's engineers, calculation depends primarily on the following factors:

1. Incoming Links
2. On-page Optimization
3. Web Site Age
4. Site Structure

This term refers to Web traffic directed from external sites. A Web site's PageRank increases when it receives incoming links. Also, the positive effect is determined in part by the PageRank of the external site. Incoming links not only boost PageRank; they also provide traffic from a specific audience. Since this audience is being directed from a related site, the quality of traffic from an incoming link is generally better than other forms of traffic.

This topic spans a wide variety of SEO techniques. To give a brief overview, on-page optimization refers to techniques used within a Web page to increase its PageRank and keyword rankings. A few aspects include:

1. Using page titles in the tags - Target keywords can be used in title tags, but not spammed or overused. Spamming keywords actually penalizes a Web site's keyword ranking ability.
2. Using description and keyword Meta tags - Again, some keywords can be used in the tags but not too many. Even though the keyword tags seem relevant, they don't actually carry much weight in SEO.
3. Linking internally - A method of passing importance to the deserving pages. This also helps by passing keyword strength to specific pages.
4. Using special importance tags - These include bold, strong, and heading tags. These tags are the primary method of on-page optimization because they highlight keywords without overstressing them. It is most effective to target no more than two keywords on any given page.
5. Using the filename - The filename of a page has been thought to carry some relevance to keyword rankings. If a Web site needs to target a keyword like "baseball gloves," then the developer will use a filename like "baseball-gloves.php" or "baseball-gloves.html" to increase keyword density. Dash marks are more effective than underscores because Google reads the former as spaces.

It is widely believed that a certain amount a time must pass before a new Web site begins gaining PageRank. However, this theory is not fully proven. More likely a Web site can begin gaining PageRank as soon as its domain is registered and pointing to unique content, but no significant increases take place until links are exchanged. The earlier a site begins exchanging links, the sooner it will gain PageRank.

Clean site structure allows the Spider to crawl through a Web site and log it more accurately. The Spider just follows links; it does not pass through forms such as username and password logins. Also, error pages and broken links will negatively affect the crawling process. In order to guarantee that there are no crawling problems with a page, developers use the "robots" Meta tag. If a page contains a form, duplicate content, or errors, then the code "nofollow, noindex" can be used inside the "robots" Meta tag. This tag belongs at the top of the page to guide the Spider.

Depth is another important issue regarding site structure. The Spider seems to travel only three links from any given page. This means that content found four or more pages from the Web site index will not be discovered in the crawling process. To solve this problem, developers build a sitemap using XML and upload the file to Google. The sitemap can be re-uploaded each time the site is updated to increase the rate of Spider visits.