What Is a Search Engine?

              The search engine is a program, designed to identify and respond to the specific questions (or) keywords to give the user required results in SERP(search engine results page).

             There are many types of search engines some of them are  GOOGLE, YAHOO, BING, ASK.COM, DuckDuckgo, SAFARI, MSN SEARCH, SEARCH.COM.

              These Search Engines are used to get Web Searches.

               In the (SERP) Search Engine Results Page the Results may be the links of Web Pages, Images, Videos, Articles, Infographic(knowledge graph) & Research pages, and other types of files. Unlike web directories, which are maintained only by human editors, search engines also maintain real-time information by running an algorithm on a web crawler. Internet content that is not capable of being searched by a web search engine is generally described as the deep web. 

                                              

                                       

Overview of How does Search Engine Works.

The search engine works under three stages

they are
-CRAWLING
-INDEXING
-SEARCH RESULTS

SO WHAT IS WEB CRAWLER?

The web crawler is also known as a spider or spider bot. the crawler is software in the search engine.

the search engine systematically sends the spider bot into the world wide web into the billions and billions of websites to crawl the required pages from the websites on the web and compiles the information into specific folders and sent for indexing.

The architecture of a Web crawler