#3 : Search Engines & Online Database

What is Search Engine?
Search Engine is a web tool that allows users to enter keywords and find information on websites contained in its database. Search Engines like Google or Yahoo uses software that collects data from the Web to include in its database.


There are four items that make up a search engine:

• database 
• web-crawlers / spider 
• information retrieval system 
• user interface 

What is Database?

Database is a storage where all indexed webpages are stored and it contains only essential information of a Webpage. This is where the user’s query is matched.








What is Web-crawlers / Spiders?


Web-crawlers or Spiders is an automated program or bot that “crawls” all over the Web Page collecting information by:

• Keywords
• Titles
• Synonyms
• Access Frequency
• Relevancy

Information is indexed and stored in the database.







What is Information Retrieval (IR) system?

Information Retrieval (IR) system is a system used to match the user's query to indexed webpages found in database. Results presented in rank according to the relevance.


This is the example on how information retrieval system works.







What is User Interface (UI)?


User Interface (UI) is a user-friendly app/site/page where users may input query and search results are presented.




There are also things like Specialized Search Engines and Meta Search Engines.


What is Specialized Search Engines?


Specialized Search Engines are search engines tailored to search for a specific area. Its database only stores Webpages relevant to a specific field.

• Google Scholar
• Education World
• Art cyclopedia
• Pipl.com 

What is Meta Search Engines?
Meta Search Engine is a search engine that matches the user's query to multiple search engines such as:


–MetaCrawler
–SavvySearch
–Dogpile