Search Engine and its types
by Muhammad Yousuf Ali
Search Engine
Multiple websites indexing a program that searches for and identifies items in a database that correspond to keywords or characters specified by the user, used especially for finding particular sites on the World Wide Web.
OR
A search engine is a web site that collects and organizes content from all over the internet.
History of Search Engine
Foundation date of the renown search engine are mentioned as under;
Jump Station, 1993 The father of search engine Jonathon Fletcher
Yahoo was founded by David Filo and Jerry Yang in 1994
Ask.com (originally known as Ask Jeeves) is a question answering search engine, founded in 1996 by Garrett Gruener and David Warthen
Google was founded in 1998 by Larry age and Sergey Brin
Bing owned and operated by Microsoft Launched in 2009
Types of Search Engine
There are four types of search engines;
• Crawler based search engines
• Directories
• Hybrid search engines
• Meta search engines
1.Crawler based search engines
Search engines use a "spider" or a "crawler" to search the Internet. The crawler digs through individual web pages, pulls out keywords and then adds the pages to the search engine's database. Google and Yahoo are examples of crawler search engines.
The advantage of crawlers are:
• They contain a huge amount of pages.
• Ease of use.
• Familiarity. Most people who search the Internet are familiar with Google.
2. Directories
Directories are human-powered search engines. A website is submitted to the directory and must be approved for inclusion by the editorial staff. Open Directory Project and the Internet Public Library are examples of directories.
Examples:
• Yahoo Directory (www.yahoo.com)
• Open Directory (www.looksmart.com)
3. Hybrid search engines
Hybrids are a mix of crawlers and directories. Sometimes, you have a choice when you search whether to search the Web or a directory. Other times, you may receive both human-powered results and crawler results for the same search. In this case, the human results are usually listed first.
Examples:
· Yahoo.com
· Google.com
4. Meta Search Engine
Meta-search engines are ones that search several other search engines at once and combines the results into one list. While you get more results with Meta-search engines, the relevancy and quality of the results may sometimes suffer. Dogpile and Clusty are examples of Meta search engines.
Examples:
· Dogpile
* Clusty
