SEO Learning Center >> How Seach Engines Work

How Does a Search Engines Work Anyway?

How do search engines work and what can I do to help them find my website? These are common questions among webmasters, and I promise to answer both of them for you in this tutorial on how a search engine works.

Before you can understand how to improve your website's visibility, you must know the basics of how a search engine works. And just so we're on the same page, let's start with a definition.

What's a Search Engine?

A search engine is an Internet-based tool that identifies websites based on search terms you have entered. These terms are referred to as keywords and key phrases.

There are hundreds of search engines online today, but many of them live in "quiet obscurity." Google is the best known of all the search engines and therefore gets the most users. Yahoo, MSN (Live Search) and Ask are other popular options.

Search engines create databases (or "indexes") through the use of robotic crawlers. These robotic web crawlers are often called spiders because of the way they crawl the web. Both terms — crawler and spider — signify the way these robotic components scour the web automatically in search of websites to index.

When search engine crawlers find a particular website, they then crawl through the various pages of that site to determine what it's about. If the site has a good navigation system in place, crawlers can follow the hyperlinks from page to page, much the same way as a person would.

In this way, the search engine can identify what the website is about (or what it thinks the website is about) and thus how to categorize it.

In Plain English - Search engines work like this: They crawl the web automatically and constantly. When they find new websites, they add those sites to their database. So when you search through Google, you are actually searching Google's database, and not the "live" Internet.

How Search Engines Work

Although they determine their results differently, all search engines operate the same:

1. The searcher enters a key phrase into a search engine.
2. The search engine searches its database (or "index") to find matches.
3. The search engine displays the results in a ranked order based on relevancy.

All search engines perform steps one and two in basically the same fashion. Step three is where they differ. Each site uses a different formula (or "algorithm") to determine which results get the highest ranking, the second-highest ranking, the third-highest and so on.

These algorithmic factors also represent things you can do to improve your ranking, which is the entire purpose of search engine optimization.

Related item: What's a directory?