How Search Engines Work.
Many people wonder how search engines really work. Although the details are complex, this article aims to give you some insight into the process without getting too technical. Read on…
Most search engines have three parts: a crawler, an index, and a search interface. Let’s look at each part individually, to get a better understanding of them. Each part has its own role to play in the process, with all the parts working together to make searches possible.
The Crawler.
Also known as a ’spider’ or ‘bot’, this part of the search engine wanders the web, following links and picking up information for its database. Crawlers do most of their work at times of the day when search engines are less busy, but they typically visit frequently updated pages more often. This is something to keep in mind when you’re working on your pages. As you may want to perform updates locally and update them when they have been finished rather than updating bits and pieces and hoping that the search engine runs into the correct version.
Also, crawlers ignore some things: your site’s code, for example. Your site’s title and text - your ‘content’ - is the most important thing to a crawler. The fastest way to raise your site’s search engine ranking for specific key words is to implement them into your title and your content.
The Index.
Once the crawler has collected all that text, it is then stored and indexed. This allows people searching for keywords and phrases to get results relating to what they were searching for - their search results. Most sites will incorporate rating systems such as Google Page Ranks or Alexa rankings in positioning your site. These ratings are used to attempt to ensure that sites that are important receive more traffic than unimportant sites.
To see this in action, go to a search engine and type in a word. You’ll see some text on the page saying something like “results 1-10 of 345,000″. This means that the search engine’s index contains 345,000 pages it believes are related to the word you typed. If you wanted to, you could look through all these pages to find the information you’re looking for.
In order to understand rating systems more thoroughly consider your own site. When you place links on your site you generally due so in order to increase your users understanding of the content of your site. If every site in a particular field links to a particular site, this site is probably very important to that field and should, therefore, be listed highly in the lists of search engine results. Thus the basic ideology of Google Page Ranks.
Consider again, a site that receives a great deal of traffic. If a site is receiving loads and loads of traffic, it probably has some information or service that is very important to its users. Alexa ratings attempt to estimate the amount of traffic that a particular site gets and compare it to the amount of traffic that other sites get. The closer that a site is to the most trafficked site on the internet, the more likely it is to have important content if it is relevant to the search query.
The Interface.
Search engines provide a public interface for users who want to find information on the web. They can type the word or phrase they’re searching for, and the interface will run an algorithm to find the pages relevant to their search and display them.
These algorithms are an important part of the SEO (search engine optimization) business, and the search engines are constantly changing them. You’ll notice when the algorithms change, as the rankings of your website will change with them.
No two search engines are the same. They all work differently, with their own unique features, and they will all respond to your website in their own way. You should familiarize yourself with the most popular search engines, to better understand how each of them works.
The most popular search engines today include Google, Yahoo, AltaVista, AllTheWeb, MSN, and Ask Jeeves. There are many other search engines available, though, and you shouldn’t ignore them altogether.
When you submit your website to the search engines, there’s no way of knowing when they might add it to their indexes. Since each search engine has its own crawling and indexing methods, you can’t be sure how long it might take. In some cases, you might see results within a week, but don’t count on it - it may take several weeks or even months before you see anything.
It’s not easy to get a high ranking unless you spend some time on it, and learn the proper methods. When you take the time and do some research, you’ll find that it’s not as confusing as you first thought. Learning the basics will enhance your experience more than you would have thought possible.



Source:SEO tutorials: How Search Engine Works « SEO Demystified