The Web is filled with more data than there are Stars in the Universe. About 5 new websites and innumerous blogs are launched every second, and the only single way for extracting relavent data in this overly convoluted web is through a Search Engine, which has become a part and parcel of everybody’s lives. Its tough to imagine a day without Google. So when it is so important to us, why not ponder in as to how this works.
The term “search engine” is often used generically to describe both crawler-based search engines and human-powered directories. These two types of search engines gather their listings in radically different ways.
Crawler-Based Search Engines
Crawler-based search engines, such as Google, create their listings automatically. They “crawl” or “spider” the web, then people search through what they have found.
If you change your web pages, crawler-based search engines eventually find these changes, and that can affect how you are listed. Page titles, body copy and other elements all play a role.
For a animated explanation of a Crawler Based Serch Engine Click Here.
A human-powered directory, such as the Open Directory, depends on humans for its listings. You submit a short description to the directory for your entire site, or editors write one for sites they review. A search looks for matches only in the descriptions submitted.
Changing your web pages has no effect on your listing. Things that are useful for improving a listing with a search engine have nothing to do with improving a listing in a directory. The only exception is that a good site, with good content, might be more likely to get reviewed for free than a poor site.
“Hybrid Search Engines” Or Mixed Results
In the web’s early days, it used to be that a search engine either presented crawler-based results or human-powered listings. Today, it extremely common for both types of results to be presented. Usually, a hybrid search engine will favor one type of listings over another. For example, MSN Search is more likely to present human-powered listings from LookSmart. However, it does also present crawler-based results (as provided by Inktomi), especially for more obscure queries.
Google goes a step ahead with its Page Rank System.
Also Check out its PigeonRank System check out more here. 😉
An important related area is Search Engine Optimization, which is basically improving quality and traffic to a website by listing it early on Search Pages using proper ranking.. Check it out here on wiki.