Off-page optimization (off-page SEO) is what can be done off the pages of a website to maximize its performance in search engines for target keywords related to the on-page content and keywords in off-page direct-links.
Off-page optimization is a very important part in search engine optimization because it gives back links to you site and it requires a lot of work.
It helps to maximize website performance in search engines for targeted key phrases.
Off - Page SEO Opportunities
Search Engine/Directory Submission (DMOZ, Best of the Web)
Social Book Marking Submission (twitter, digg.com, del.icio.us)