What is SEO (part 2)

It is common to hear that SEO is living an evolving phase. It is true.
However it is also true that SEOs, instead, are living a confused phase. SEO as Inbound or Content Marketing or both or not being SEO anymore.
In this post Gianluca Fiorelli will try to clarify the nature of SEO describing what it is making it unique, starting from its very metrics.