What is Deep linking..?

Answer 1

Deep linking, on the World Wide Web, is making a hyperlink that points to a specific page or image on another website, instead of that website's main or home page. Such links are called deep links

Answer 2

A hyperlink either on a Web page or in the results of a search engine query to a page on a Web site other than the site’s home page. Typically, a Web site’s home page is the top page in the site’s hierarchy, and any page other than that is considered “deep.”
For example, if a Web site linked to the Webopedia page http://www.webopedia.com/Term/D/deep_link.html, this would be considered a deep link because the site linked to one of Webopedia’s pages other than its home page, http://www.webopedia.com