Ethiopian Treasures

What are search engines?

Search engines are programmes (tools) that help you find websites or information on the Internet using keywords. The Internet contains a large volume of information in all subjects which is freely accessible for everyone who has access to the Internet.

Searching is required by entering a keyword or keywords in the search engine's search box when you want to find information on the Internet, as yet, you do not know the address of a website to visit to find it. However, search engines require the use of good search techniques in order to make the search process more efficient and find the required information without being overwhelmed with a huge amount of irrelevant information.

How do search engines actually work?

The goal of search engines is to seek out web pages on the Internet and create a quick reference to their location. Most search engines use robots, spiders or crawlers that navigate through the web or wander around the web following the links on pages, when they find the information, they copy the information back to their database. Crawlers often rely on the way the HTML within pages is constructed to index the page. Robots look for Meta tags to determine what the page is about, and keywords within the text. This gives the robot some idea of the general construction of the pages.

What types of search engines are there?

1. Directory based search engines

Directory based search engines rely solely on the web page authors visiting the search engines and/or registering directly. Other search engines use the Meta tags supplied by the website designers or keywords in the home page to rank according to relevance. Search engines like Yahoo, LookSmart, MSN, Open Directory, EuroSeek and MegaGo, for example, are based on the directory model which puts websites into categories which are then divided into sub-categories.

2. Hybrid search engines

Hybrid search engines use both a directory and a search engine. For example, Google, ExactSeek, Lycos and Altavista are hybrid search engines which use a Directory to supplement their own search engines. However, Google also employs different techniques by examining and organising the links on websites into topics to determine the most relevance of the information. Its search features include the unique "I'm feeling lucky" button, which takes you directly to the first website in the list of results. Undoubtedly Google is the most efficient search engine, as it is very rare to find a non-working link.

3. Meta search engines

Meta search engines search multiple search engines and directories simultaneously and return the most relevant information. WebCrawler, MetaCrawler, Exite and Ixquick are good example of meta search engines and they often search the most popular search engines and directories such as Google, Alltheweb, Teoma, Yahoo, Altavista, Lycos, HotBot, Fast, Ask Jeeves, Excite, Inktomi, LookSmart, Open Directory and About.

4. Natural language search engines

Some search engines are now looking at new ways of finding information by using a different approach i.e. natural language search engine. A good example of a natural Language search engine is Ask Jeeves. Instead of using keywords to find the required information, web users can simply type in their question using natural language. Some examples of the questions which work well are:

1. Where can I find information about Egyptian Pyramids?

2. What is the longest river name in the world?

You can try this for yourself by using the following search engines which work with natural language i.e. Ask Jeeves at www.ask.co.uk

The number of different types of search engines are listed into several major types below and just click one of the search engines you wish to use.

Search Engines

• AlltheWeb
• WiseNut
• HotBot
• Teoma

Directory Based Search Engines

• Yahoo
• LookSmart
• MSN
• Open Directory
• EuroSeek
• MegaGo

Hybrid Search Engines

• Google
• Altavista
• ExactSeek
• Lycos

Meta Search Engines

• WebCrawler
• Excite
• MetaCrawler
• Ixquick
• ez2Find
• Kartoo

Natural Language Search Engine

• Ask Jeeves

Subject Specialists Search Engines and Directories

• About: Expert Guidance and Subject Resources
• Whatis.com: IT Encyclopedia
• Buildfind.com: Construction Search Engine
• EngNet: Engineering Directory
• The WWW Virtual Library
• SOSIG - The Social Science, Business and Law Information Gateway
• EEVL: Engineering, Mathematics and Computing
• BIOME: Health, Medicine and Life Sciences
• GEsource: Geography and Environment Information Gateway
• Humbul Humanities Hub
• Infoplease: Encyclopedia, Atlas and Almanac
• PSIgate: Physical Sciences Information Gateway
• MSN Encarta - Online encyclopedia, Dictionary, Atlas and Homework

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