Search engines - what are they and which are the most important?

What is a search engine?

Wikipedia defines a search engine as: "...a document retrieval system designed to help find information stored on a computer system, such as on the World Wide Web, inside a corporate or proprietary network, or in a personal computer."

Basically, this means computer programs that gather and categorise information on the Internet.

According to some surveys, more than 86% of all visitors arrive at websites via search engines, which means that you can't afford to ignore search engines!

Which are the most important search engines?

Reportedly, Google accounts for 70% of search engine traffic and is acknowledged to the search engine of choice for many surfers. This is followed in popularity by Yahoo! and then Bing (formerly Bing (formerly MSN)). Other search engines follow behind.

Google is currently said to have indexed 8 billion web pages, and counting.