Search Engines allows people to discover content across the web through their software system based on keywords and phrases given by the searchers and the sites' relevance.
What is a search engine?
A web search engine or Internet search engine is a software system designed to carry out web search (Internet search) based on a query (keyword or phrase) and display the most relevant websites as a result.
How do search engines work and how many of them are there?
Search engines get the information from spider (crawlers) by crawling websites from a link to another one, and by checking the sitemaps and robots.txt files.
The world's most frequently used search engines are: