The Italian language adopted by the state after the unification of Italy is based on Tuscan, which beforehand was a language spoken mostly by the upper class of Florentine society. Its development was also influenced by other Italian languages and by the Germanic languages of the post-Roman invaders.

Italian is descended from Latin. Unlike most other Romance languages, Italian retains Latin's contrast between short and long consonants. As in most Romance languages, stress is distinctive. Among the Romance languages, Italian is the closest to Latin in terms of vocabulary.