This document provides an overview of search engines. It defines a search engine as a program that searches databases for keywords specified by users, especially used to find websites. The document then discusses the history of search engines from 1990 to present day, how search engines work by crawling, parsing, and indexing web pages, different types of search engines like hybrids and meta search engines, why search engines are useful, and some limitations.

1. Search Engine
Presented by
Shanta Rayamajhi Basnet
Roll.no. 76155010
Nepal Open University

2. Contents
 What is search engine?
 History of Search engine
 How does it work?
 Types of Search Engine
 Why Search Engine?
 Disadvantages of Search Engine

3. What is Search engine:
 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.
 Online tools that helps user to search through vast data over
internet for a specific query.
 Examples: Google, yahoo, bing, duckduckgo ,etc.

4. History of Search Engines
 1990– The first search engine is Archie. However, the limited data
made only the listings available, not the content.
 1991– Tim Berners-Lee, the inventor of the WWW, created a virtual
library to help users find URLs for different websites.
 1993– Jump Station brought a new leap with their linear search which
showed a page’s title and header in the same results.
 1994– David Filo and Jerry Yang create Yahoo! Search. The site was
the first collection of web pages across the internet. They include man-
made descriptions for the URLs.

5. History of Search Engines
 1996- Larry Page and Sergey Brin created the predecessor to
Google BackRub.
 1998– Google officially launches.
 Today- Google have over 75 percent of the search market share.

6. How does it work?
 Scheduling
 Assesses the relative importance of new and known URLs.
 Decide when to crawl new URL.
 Crawling
 Downloads content of web pages.
 Passes downloaded webpage to parser.

7. How does it work? (cont. )
 Parsing
 Extracts links from the page, along with other key information.
 Sends extracted data for indexing.
 Indexing
 Adding information from crawler to Database called search index.
 digital library of information about trillions of web pages.

8. Types of Search Engines:
 Hybrids
 mix of crawlers and directories.
 Can choose whether to search the Web or a directory.
 Meta
 several other search engines at once and combines the results into one list.
 Dogpile
(Dogpile is a metasearch engine which collects search results from multiple
different search engines including Google, Yahoo, Bing and a few others)

9. How does it work? (cont. )

10. Types of Search Engines
 Crawlers
 These types of search engines use a "spider" or a "crawler" to search the
Internet.
 Google and Yahoo are examples of crawler search engines.
 Directories
 Human powered search engines.
 A website is submitted to the directory and must be approved for inclusion by
editorial staff.
 Open Directory Project and the Internet Public Library are examples of
directories.

11. Why Search Engine?
 Quick search in vast amount of data.
 Can search data according to user specified query.
 Can locate data that normally is very hard.
 Can search for specified format like using google dorks.
 Keeps internet/www in systematic order.

12. Limitations:
 May show tons of unrelated results.
 Matter of privacy as anyone with internet can search through search engine.
 Makes people more dependent.
 Make developers hard to hide some content that was not intended for
everyone.

13. References
 https://libguides.astate.edu/c.php?g=14516&p=78177
 https://en.wikipedia.org/wiki/Web_search_engine
 https://www.bigcommerce.com/ecommerce-answers/how-does-search-
engine-work/
 https://ahrefs.com/blog/how-do-search-engines-work/
 https://www.slideshare.net/AdarshkumarYadav/search-engine-72427771