Search engine crawlers and their importance for an SEO

A search engine optimization specialist would know the importance of spiders in SEO and how a webpage can be tweaked or manipulated with respect to the spiders. Spiders play a pivotal role in the working of a search engine. Spider or a web spider is a computer program that browses the World Wide Web in an automated and methodical manner. Also known as ants, bots, automatic indexers, worm, Web robot and web scutter - spiders come in various names but almost perform the same role.

The success of the various strategies of internet search engine optimization employed is dependent on the report provided by spiders or crawlers.

Crawling - the mechanism

The process of browsing performed by the web spider is called crawling or web crawling .The web crawler, a type of software agent or bot starts the process by visiting a list of URL's called the seeds. It identifies all the hyperlinks in the list of URL's (i.e. seeds) and adds them to the crawl frontier, which is the list of URL's to visit further. The list of URL's from the crawl frontier is visited regularly abiding a set of policies.

The behavior of the web spider is based on the combination of the following policies:

• A selection policy: It states which pages to be downloaded.
  
• A re-visit policy: It states when to revisit or re-check the pages for changes in it.
  
• A politeness policy: It states how to avoid the overloading of WebPages or websites
  
• A parallelization policy: It states how to co-ordinate the various distributed web crawlers.

Usage of spiders

Crawlers or spiders can be used automated maintenance tasks of a website such as validating HTML code or checking links. Spiders can also be used to gather certain information from websites like collecting e-mail addresses (possibly for spam).

However, the primary usage of spiders is by the search engines. Search engines use crawlers to provide up-to-date data about the World Wide Web. It is used to create a copy of all the pages visited for processing by the search engines, which will index the downloaded pages. The road to increasing traffic begins with spiders and that's the reason for spiders to be of utmost importance to search engine optimization companies and SEO specialists alike.