Romance language spoken by some 66,000,000 persons in Italy (including Sicily and Sardinia), France (including Corsica), Switzerland, and other countries. It is spoken by large numbers of emigrants and their descendants in the Americas, especially in the United States, Argentina, and Canada. Written materials in Italian date from the 10th century (a set of court records with the testimony of the witnesses in the Italian vernacular), and the first literary work of length is the Ritmo Laurenziano (“Laurentian Rhythm”) of the late 12th century.

Although Italian has a standard literary form, based on the dialect of Florence, the common speech is dialectal or a local variant of standard Italian. The less formal the occasion and the less educated the speaker, the greater the deviation from standard speech; many Italians cannot speak the standard language at all. The following dialect groups are distinguished: Northern Italian, or Gallo-Italian; Venetan, spoken in northeastern Italy; Tuscan (including Corsican); and three related groups from southern and eastern Italy—(1) the dialects of the Marche, Umbria, and Rome, (2) those of Abruzzi, Puglia (Apulia), Naples, Campania, and Lucania, and (3) those of Calabria, Otranto, and Sicily.

The sound system of Italian is quite similar to that of Latin or Spanish. Its grammar is also similar to that of the other modern Romance languages, showing agreement of adjectives and nouns, the use of definite and indefinite articles, loss of noun declension for case, two genders (masculine and feminine), and an elaborate system of perfect and progressive tenses for the verb. The most notable difference between Italian and French or Spanish is that it does not use -s or -es to form the plural of nouns but instead uses -e for most feminine words and -i for masculine words (and some feminine words).