subject: Inside the Search Engines [print this page] Inside the Search Engines Inside the Search Engines
Have you ever wondered when you go to the internet, open up google.com or yahoo.com, type in some search item and get the results in a moment, what exactly happens behind the scene? Well, actually a lot of complex things go into all these. Let's try to understand what exactly goes on. With some technical support, let's learn more about search engines.
A web search engine is designed to search for information on the World Wide Web. The search results are usually presented in a list of results and are commonly called hits. The information may consist of web pages, images, information and other types of files.
Now the question is how does a web search engine work? Basically it operates in the following ways.
How Search Engine Works
Web search engines work by storing information about millions of web pages. These pages are retrieved by a Web crawler (sometimes also known as a Spider) an automated Web browser, which follows every link on the site.
The contents of each page are then analyzed to determine how it should be indexed (for example, words are extracted from the titles, headings, or special fields called meta tags).
Data about web pages are stored in an index database for use in later queries. A query can be a single word. The purpose of an index is to allow information to be found as quickly as possible.
When a user enters a query into a search engine (typically by using keywords), the engine examines its index and provides a listing of best-matching web pages according to its criteria, usually with a short summary containing the document's title and sometimes parts of the text.
The usefulness of a search engine depends on the relevance of the result set it returns back. While there may be millions of web pages that include a particular word or phrase, some pages may be more relevant, popular, or authoritative than others. Most search engines employ methods to rank the results to provide the "best" results first. How a search engine decides which pages are the best matches, and what order the results should be shown in, varies widely from one search engine to another. The methods also change over time as Internet usage changes and new techniques evolve.
Types of Search Engines
There are two main types of search engine that have evolved: one is a system of predefined and hierarchically ordered keywords that humans have programmed extensively. The other is a system that generates an "inverted index" by analyzing texts it locates. This second form relies much on the computer itself to do the bulk of the work.
Where Does the Money Come From?
Most web search engines are commercial ventures supported by advertising revenue and, as a result, some employ the practice of allowing advertisers to pay money to have their listings ranked higher in search results. Those search engines, which do not accept money for their search engine results make money by running search related ads alongside the regular search engine results. The search engines make money every time someone clicks on one of these ads.
List of Search Engines
Below is a list of some of the search engines and their year of launch:
