"There is internal and external SEO. Internal makes up about 15% of the process and it means to design your site so it follows the best practices proven to rank high on Google. External SEO used to mean to write articles, press releases, blogs, comments, and content with hypertext keyword “backlinks” to your site. Now it is changing fast to include social media strategies.
SEO has been traditionally divided into “white hat” or “black hat.” Black Hat is the obvious villainous practice of gaming the system by doing things to raise rankings that Google doesn’t want, and White Hat is just more subtle.
So, what does Google want?
So by definition even the word Search Engine Optimization (SEO) means to “game” the Google search engines (and others) to get your valuable content ranked higher than it would be if left alone to the forces of the Web.
Google decided to change their weighted emphasis from “backlinks” to social media likes, shares, tweets, reddits, and 1+ (Googles obvious favorite.) In the world of digital media the emphasis is on follows, comments, and views as well.
What does that mean? Now Google seems to believe that if you promote content with social media it is more indicative of relevant content and less likely to be faked".
Via Antonino Militello