This page is a part of the Spanish Wine FAQ.
There are strict procedures required of wines (and indeed all foodstuffs that belong to such a designation) before they can be labeled with a denominación de origen. Primarily, it applies to where the wine is made, but it also affects such things as the types of grapes that can be used as well as the manufacturing process.
In recent times, some wine producers have become dissatisfied with the denominacion de origen system, believing that such a strict system is not necessary for a wine to be of good quality - instead they make wine known as vino de la tierra.
Thanks to Mary O´Connor of Planeta Vino Wine Tasting School, Madrid for her help with this page.