One important thing of the search engine optimization is creating backlinks for your website(s). Google does not put in consideration as before the page rank based on these backlinks, but it is important: it is one of the things that make the difference when duplicate content appears (from any reason at all). The backlinks remain important by themeself because the are "points of entrance" of the people that sees the link, consider the title important and follows it. If your content really is interesting, and people like it, when the potential visitor sees another links from the same website he/she may conside following them base on the good impresion from the previous visit.
Backlinks on social media is a distinct part of the SEO. If the "regular" backlinks remain online for weeks, months or even years (depending the targeted website) the social media links to your website usually remain in other people attenion for hours or, in happy cases, weeks. In the best cases the content of the article you are linking at can become viral and you will get hundreds or thousands visits in matter of hours.
When creating backlinks you can either add them manually or to create/use scripts that do it for you automatically. The search engine will see them all (if you give them enough time) and they will consider/index some of them, depending on the established links. The human visitors will consider only the links they see and found interesing... so our advice is to combine automatic and manual backlinking, regular backlinking and social media. For more detailes informatios contact us... we offer consultancy and SEO services for clients.