Spain developed their Denominación de Origen (D.O.) wine system in 1932, and it has been updated several times to reflect improved quality. The system has similarities with the rating Appellation d'Origine Protégée (AOP) system of France, Portugal's Denominação de Origem Controlada (DOC) and Italy's Denominazione d'Origine Protetta (DOP).
Spain has around 80 quality wine regions under some form of geographical classification. In addition there is Denominación de Origen Calificada (DOCa or DOQ in Catalan) status for DOs that have a consistent track record for quality.
There are currently three DOCa / DOQ regions: Rioja, Priorat and Ribera del Duero. Each DO has a Consejo Regulador, which acts as a governing control body that enforces the DO regulations and standards involving viticultural and winemaking.

 

These regulations govern everything from the types of grapes that are permitted to be planted, maximum yields that can be harvested; the minimum length of time that the wine must be aged and what information is required on the wine label. Wineries that are seeking to have their wine sold under DO or DOCa status must submit their wines to the Consejo Regulador laboratory and tasting panel for testing and evaluation. Wines that have been granted DO/DOCa status will feature the regional stamp of the Consejo Regulador on the label.
Following Spain's acceptance into the European Union, Spanish wine laws were brought in line to be more consistent with other European wine systems. One development was a five-tier classification system that is administered by each independent region. Non-independent areas or wine regions whose boundaries overlap with other independent communities (such as Cava, Rioja and Jumilla) are administered by the Instituto Nacional de Denominaciones de Origen (INDO) based in Madrid.

The 6-Tier Wine Classification System of Spain includes:
• Vino de Mesa (VdM) - These are wines that are the equivalent of most country's table wines and are made from unclassified vineyards or grapes.
• Vinos de la Tierra (VdlT) - This level is similar to France's vin de pays system.
• Vino de Calidad Producido en Región Determinada (VCPRD) - This level is similar to France's Vin Délimité de Qualité Supérieure (VDQS) system and is considered a stepping stone towards DO status.
• Denominación de Origen (DO) - Nearly two thirds of the total vineyard area in Spain is within the boundaries of a DO region.
• Denominación de Origen Calificada (DOCa / DOQ) - This designation, which is similar to Italy's Denominazione di Origine Controllata e Garantita (DOCG) Rioja was the first region afforded this designation in 1991 - then Priorat in 2003 and Ribera del Duero in 2008.
Plus there is • Vino de Pago (VP) - this designation is for individual single-estates with an international reputation - there are currently 14 estates with this status.