Search Engine Details and Components

SEARCH ENGINE

Search Engine refers to a huge database of internet resources such as web pages, newsgroups, programs, images etc. It helps to locate information on World Wide Web.

User can search for any information by passing query in form of keywords or phrase. It then searches for relevant information in its database and return to the user.



Search Engine Components

Web Crawler
Database
Search Interfaces
Web crawler
It is also known as spider or bots. It is a software component that traverses the web to gather information.


Database
All the information on the web is stored in database. It consists of huge web resources.

Search Interfaces
This component is an interface between user and the database. It helps the user to search through the database.

Working

Web crawler, database and the search interface are the major component of a search engine that actually makes search engine to work. Search engines make use of Boolean expression AND, OR, NOT to restrict and widen the results of a search. Following are the steps that are performed by the search engine:

The search engine looks for the keyword in the index for predefined database instead of going directly to the web to search for the keyword.
It then uses software to search for the information in the database. This software component is known as web crawler.
Once web crawler finds the pages, the search engine then shows the relevant web pages as a result. These retrieved web pages generally include title of page, size of text portion, first several sentences etc.
User can click on any of the search results to open it.
Architecture

The search engine architecture comprises of the three basic layers listed below:

Content collection and refinement.
Search core
User and application interfaces
Examples

Search Engine Description
Google It was originally called BackRub. It is the most popular search engine globally.
Bing It was launched in 2009 by Microsoft. It is the latest web-based search engine that also delivers Yahoo’s results.
Ask It was launched in 1996 and was originally known as Ask Jeeves. It includes support for match, dictionary, and conversation question.
AltaVista It was launched by Digital Equipment Corporation in 1995. Since 2003, it is powered by Yahoo technology.
AOL.Search It is powered by Google.
LYCOS It is top 5 internet portal and 13th largest online property according to Media Matrix.
Alexa It is subsidiary of Amazon and used for providing website traffic information.