VdT: Vino da Tavola
A basic wine made in Italy.(table wine)

IGT: Indicazione Geografica Tipica
A wine from a specific Italian region. This appellation was created for wines of higher quality than simple table wines, but which did not able to reach DOC appelation

DOC: Denominazione di Origine Controllata.
DOC denomination refer to specific zones (more than an IGT), specific rules and specific grapes.
These rules are designed to preserve the traditional wine-making practices of the individual regions: it means that different wines have different rules of production.
The DOC system began in 1963, seeking to establish a method of both recognizing quality product and maintaining the international and national reputation of that product.