Search Engine a website or a program that allow users to search on World Wide Web by entering phrases or queries or keywords. Query is something that user want to search, that user writes in search box it could be some numbers, set of words or symbols etc.
After searching in search box, result appears in a line technically called SERP i.e. Search Engine Result Page. Search engines gives result in text, images, videos, news etc. Some search engines also shows real time search results.
Most popular examples of search engines are Google, Yahoo!, and MSN Search. Search engines utilize automated software applications (referred to as robots, bots, or spiders) that travel along the Web, following links from page to page, site to site. The information gathered by the spiders is used to create a searchable index of the Web.
Archie was the first tool used for searching over the internet and Veronica was the first text based search engine. Google is the widely used Search engine in current scenario.
How search engine work –
Web crawling – Crawlers or spiders crawls the web pages they retrieve the information from the html mark-up of web pages. After analysing the web page, web crawler store the information of title, Meta tags, descriptions, heading etc. Data of webpages stored in an index database to be used in search queries. Search engines uses index database to find users queries relative results.
When a user enter a query to search box, search engine examine the query based on it algorithm and find the best results to user and show the list of results called SERP to user. SERP usually shows the title of result, Meta description of that page and link of the page.
SERP decides on various factors of webpages. Search Engines like Google takes less than a seconds to show user query results. Now instant search, Ajax based search is a fantastic approach by Google Search engine.