DOC or DOCG?

In Italy there two types of terms that maybe can be a little confusing, that is DOC and DOCG wines... but what's the difference between these two terms? And above all, what do these two designation of origin identify? Let's see in detail:

DOC - designation of origin - is an Italian brand that identifies only quality wines and renowned entirely produced in a given area of production and whose characteristics depend on the geographical origin;

DOCG - designation of origin guaranteed - in this case the wines are subjected to further guarantee of origin controls. The wines produced in specified geographical areas therefore must comply with one specific specification. The DOCG is reserved for wines already recognized DOC for at least ten years have been of particular value.

The DOC and DOCG marks are two acronyms that deviate from the world of classic appellations of origin but they can be assimilated to the DOP, Protected Designation of Origin.