The dialects of Italian identified by the Ethnologue are Tuscan, Abruzzese, Pugliese (Apulian), Umbrian, Laziale, Central Marchigiano, Cicolano-Reatino-Aquilano, and Molisan. On the contrary Ethnologue and the Red book on endangered languages of UNESCO consider Piemontese, Lombard, Ligurian, Emiliano-Romagnolo, Venetian, Friulian, Neapolitan-Calabrian or Tricalabrian (a range including Neapolitan, Sicilian and Calabrian) and Sardinian as regional minority languages, structurally separated from Italian. Most Italians, however, refer to these simply as "dialect", with the exception of Sardinian and Friulian, which are usually recognized language status in the regions of Sardinia and Friuli-Venezia Giulia. Also the Corsican language has strong similarities to Italian and most linguists consider it as a Tuscany dialect, the closest to modern Italian.
Many of the so-called dialects of Italian spoken around the country are different enough from standard Italian to be considered separate languages by most linguists and some speakers themselves. Thus a distinction can be made between "dialects of (standard) Italian" and "dialects (or languages) of Italy".
The dialect of Tuscany became the basis for what would become the official language of Italy, by way of the famous Tuscan author Dante Alighieri. Alighieri and other Tuscan poets were inspired by the Sicilian koine wanted by the Sicilian School under holy roman emperor Frederick II. His project (in which Giacomo da Lentini invented the sonnet) was accomplished by enriching the Sicilian language with new words adapted from French, Latin, and Apulian. The Sicilians produced a collection of love-poems which can be considered the first standard Italian ever produced, though it was only used for literary purposes until Guittone d'Arezzo. When the Svevs dynasty ended the Tuscans and Dante re-discovered it (see De Divina Eloquentia and Vita Nova) and integrated the Sicilians into Florence's linguistic heritage.
Dolce stil novo, the platonic school of courtly love can be considered the link between the old southern school and Tuscan poetry which aimed to express the new intellectual sensibility and fervor of the newly-born city-states, as Florence. Dante's work, Divina Commedia was the first of its kind to be written in a dialect (though sensibly enriched compared with its spoken counterpart), as opposed to the traditional Latin. The success of his work spread the Florentine dialect, and gave it prestige and acceptance. For this he is referred to as the father of the Italian Language.
By the time Italy was unified 1861, and Rome was annexed (1870) the Italian standard had further been influenced by Florentine through the work of the Accademia della Crusca (Cardinal Pietro Bembo and followers). Bembo laid the foundation for what is today's modern standard. But Bembo was a purist and had accepted no other influence than that from Dante, Petrarca and Boccaccio. As time went on, the language was losing touch with linguistic change, and could not put up with technology and science. The much-needed update would have to wait a little longer until, in what is commonly regarded as the first modern novel of the Italian literature, I Promessi Sposi (The Betrothed) (Alessandro Manzoni further refined its widely read novel by "rinsing" it in the waters of the Arno (Florence's river), as he states in his 1840 Preface.
However, Manzoni refused the Crusca's purist, written Florentine-only attitude and admitted a certain influence from other dialects, though he reduced it as compared to the first edition of (1821). After unification the huge number of civil servants and soldiers recruited from all over the country introduced many more words and idioms from their home dialects ("ciao" is Venetian, "panettone" is Milanese etc.), in fact confirming Manzoni's linguistic views.
Tuscan has thus become one of the twenty official dialects of Italy. Though technically speaking the division between dialect and language is purely conventional, it has been used by scholars, for eg. by Francesco Bruni, to distinguish between the languages that made up the Italian koine, and those which had very little or no part in it, as Albanian, Greek, Südtirolean, Ladino, Friulian and Occitan, still spoken by small ethnic or linguistic minorites.
Dialects are generally not used for general communication, e.g. on TV, but are limited to groups of people who can actually speak them and to informal contexts. Speaking dialect is often shunned upon in Italy as it is a sign of lacking education. Younger generations, especially those under 35 (though it may vary in different areas), speak almost exclusively standard Italian in all situations, usually with a slight local accent.
Dialects have their share of enthusiasts, but this is a small niche of the population. The promotion of dialects by some political forces as the Lega Nord has possibly damaged rather than promoted their status.
Dialects are often used in movies to provide comic relief or to produce stereotypes: northern dialects can be connected to greedy merchants; a Roman accent is associated with arrogant, simple-minded bullies; Neapolitan reminds of dishonest, cunning slackers, and, even in Italy, Sicilian is often associated with the mafia. However, many screenwriters also explore the more expressive and spontaneous features of a dialect, often to challenge the common cliches and present a richer, less explored reality.