Thanks to its long tradition and favourable climatic conditions for growing grapes, Italy is the largest wine producer in the world. To help guide the selection process, a classification is used which divides the wine into 4 categories according to quality.
VDT - Vino Di Tavola
Table wines intended for everyday drinking, for everyday consumption.
IGT - Indicazione Geografica Tipica
Regional or area wines with controlled origin.
DOC - Denominazione di Origine Controllata
Wines controlled according to origin, yield, ageing period, processing technology, etc., approximately 500 Italian wines are included here.
DOCG - Denominazione di Origine Controllata Garantita
The best wines, less than 80 top quality wines achieve this designation.
For more information on Italian wines, see e.g. here.