What are Crawlers?

A Crawler is a program that accumulates data and information from the Internet by visiting websites and reading the pages. It is used by search engines and it is also known as a spider. This program stores all data and the external and internal links in a databank. It stores information about the web page content, meta tags, web page title and much more. It helps in website indexing, it crawls one page through a website until all pages have been indexed.