You know that getting referral traffic is just as important, if not more, than organic traffic to your site. Referred visitors often land on your page due to a recommendation (in the form of a link or social share) from a trusted source. This means that these visitors aren't just casually or accidentally arriving at your site - they're already interested or engaged with your content or products.
Traditionally, Facebook has been an excellent resource - dwarfing other social networks in terms of social referral traffic. Now, Facebook has topped Google in referral traffic to media sites overall.