What is Deep Linking?
On the World Wide Web, deep linking is creating a hyperlink that points to a specific page or image on a website, instead of that website’s main or home page (per Wikipedia). Although informational links and reciprocal links are great for your visitors, deep linking is best when you are looking to gain greater rank and visibilityl.
Many website owners feel that deep linking, the ability to link freely is central to good SEO strategy.  Some of us also believe that a deep link is better than no link at all.  Deep linking may even be more profitable than a home page link, especially if the target site has a poor navigational structure
Get as many high quality backlinks as possible by asking others to exchange links.  However, make sure those links are relevant to your industry, product or service. 
Make sure you have links coming in to as many pages as possible. What does it tell a search engine when other web sites are linking to different pages on your site?  That you obviously have lots of worthwhile content.  What does it tell a search engine that all your links are coming in to the home page?  That you have a shallow site of little value, or that your links were generated by automation rather than by the value of your site. “Best SEO Tip” written By David Leonhardt: