Regional Italian, sometimes also called dialects of Italian, is any regionalvariety of the Italian language. The various forms of Regional Italian have features, most notably phonological, prosodic, and lexical that originate from the underlying substrate languages, the regional languages of Italy. The latter, especially those without political recognition, are customarily but imprecisely called dialects (), even though they are not dialects of Italian and are notably distinct from it.
Tuscan, Corsican and Central Italian, are in some respects, not distant from Standard Italian in their linguistic features because the latter was based on a somewhat polished form of Florentine.
The difference between Regional Italian and the regional languages of Italy, customarily imprecisely referred to as dialects, is exemplified by the following: in Venetian, the language of Venice, "we are arriving" would be expressed "sémo drio rivàr", quite distinct from the Standard Italian "stiamo arrivando". In the regional Italian of Venice, the statement would be "stémo rivando". The same relationship holds throughout Italy: Italian as spoken locally is usually influenced by the underlying regional language, but the regional language can be very different with regard to phonology, morphology, syntax, and vocabulary. Anyone who knows Standard Italian well can understand Regional Italian but normally cannot understand the regional languages.
Many Italian regions already had different substrata before the conquest of Italy by the Romans: Northern Italy had a Celtic substratum (that part of Italy was known as Gallia Cisalpina, "Gallia on this side of the Alps"), a Ligurian substratum or a Venetic substratum. Central Italy had an Etruscan substratum, and Southern Italy had an Italic or Greek substratum. They began as a diversification between the ways of speaking Latin, the official language of the Roman Empire.