How Does a Search Engine Work?

The purpose of a website is to communicate with people. You may be selling things, promoting a company or an organization or just wanting to spread the word about you and what you like. So, having visitors to your site is the central task about web activity, and more usual than not this is the main problem webmasters face these days.

When you have a website there are different ways to make people find it and visit it. You can send direct traffic, referring your contacts by email and other offline media or by ppc and traffic exchanges. But you can have visitors to your site simply being found in the search engines (organic or free traffic) and for this you need to understand how a search engine works.

There are two different types of search engines: crawler based (where actions are performed by programs or robots) and human based (where the indexing process is made by real people). One of the most popular search engines is Google, a crawler based search engine.

Do you know how does a search engine work? Basically it performs three actions:

Crawl or spider the web: searching for new sites and following the links to other pages. For this purpose uses small programs called crawlers or spiders that are continuously browsing the web. Spiders are directed by a crawler control module that gives the urls to visit next. When a website has been crawled or spidered is closer to be found by visitors but is not already showing up in the search engine result pages.

Index what spiders have found: storing a copy of the webpage that have been spidered. From this copy, the indexer module records the words form each page along with the URLs where this word has been found. So the index consists of a large lookup table where words are listed related to a collection of URLs relevant for these words.

Return results to search queries: presenting the most relevant results to that particular query or keyword. Results are presented following a certain order or ranking criteria, determined by formulas or algorithms used to quantify the relevance of the content against the words that the user is searching for.

Though the algorithm formulas are kept secret, the numbers of times that a particular keyword and the position in the web copy are the main factors to determine the relevance of the page for that keyword. The more relevant results are listed first in the search engine result pages.

This rank order must not be confused with the Page Rank, which is a number (between 0 and 10 in Google) that measures the relevance or popularity of the website in general and not related to a particular keyword.

Knowing how does a search engine works can give you a thoughtful insight of the aspects of the web design that you have to look after if you want a healthy and popular website. Mastering these aspects is known as search engine optimization (SEO).

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