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It is headed by a mayor (sindaco) assisted by a legislative body, the consiglio comunale (communal council), and an executive body, the giunta comunale (communal committee). The mayor and members of the consiglio comunale are elected together by resident citizens: the coalition of the elected mayor (who needs an absolute majority in the first or second round of voting) gains three fifths of the consiglio's seats. The giunta comunale is chaired by the mayor, who appoints others members, called assessori, one of whom serves as deputy mayor (vicesindaco). The offices of the comune are housed in a building usually called the municipio, or palazzo comunale.
As of February 2019 there were 7,918 comuni in Italy; they vary considerably in area and population. For example, the comune of Rome, in Lazio, has an area of 1,307.71 km² and a population of 2,761,477 inhabitants, and is both the largest and the most populated; Atrani in the province of Salerno ( Campania) was the smallest comune by area, with only 0.12 km², and Moncenisio in the Metropolitan City of Turin ( Piedmont) is the smallest by population, with 29 inhabitants.
The density of the comuni varies widely by province and region: the province of Barletta-Andria-Trani, for example, has 391,224 inhabitants in 10 municipalities, or over 39,000 inhabitants per municipality; whereas the province of Isernia has 85,237 inhabitants in 52 municipalities, or 1,640 inhabitants per municipality – roughly twenty-four times more communal units per inhabitant. There are inefficiencies at both ends of the scale, and there is concern about optimizing the size of the comuni so they may best function in the modern world, but planners are hampered by the historical resonances of the comuni, which often reach back many hundreds of years, or even a full millennium.
While provinces and regions are creations of the central government, and subject to fairly frequent border changes, the natural cultural unit is indeed the comune, for many Italians, their hometown.
Many comuni also have a municipal police (polizia municipale), which is responsible for public order duties. Traffic control is their main function in addition to controlling commercial establishments to ensure they open and close according to their license.
Administrative areas inside comuni varies according to their population.
Comuni with at least 250000 residents are divided into circoscrizioni (circonscriptions, roughly equivalent to French arrondissements or London boroughs) to which the comune delegates administrative functions like schools, social services and waste collection; such functions varies from comune to comune. These bodies are headed by an elected president and a local council.
Smaller comuni usually comprises:
- A main city, town or village, that almost always gives its name to the comune; such a place is referred to as the capoluogo ("head-place" or "capital"; cf. the French chef-lieu) of the comune; the word comune is also used in casual speech to refer to the city hall.
- Outlying areas called frazioni (singular: frazione, abbreviated: fraz., literally "fraction"), each usually centred on a small town or village. These frazioni have usually never had any independent historical existence, but occasionally are former smaller comuni consolidated into a larger one. They may also represent settlements which predated the capoluogo: the ancient town of Pollentia (today Pollenzo), for instance, is a frazione of Bra. In recent years the frazioni have become more important thanks to the institution of the consiglio di frazione (fraction council), a local form of government which can interact with the comune to address local needs, requests and claims. Even smaller places are called località ("localities", abbreviated: loc.).
- Smaller administrative divisions called municipalità, rioni, quartieri, terzieri, sestieri or contrade, which are similar to districts and neighbourhoods.
Sometimes a frazione might be more populated than the capoluogo; and rarely, owing to unusual circumstances (like depopulation), the town hall and its administrative functions can be moved to one of the frazioni: but the comune still retains the name of the capoluogo.
In some cases, a comune might not have a capoluogo but only some frazioni. In these cases, it is a comune sparso (" sparse comune") and the frazione which houses the town hall (municipio) is a sede municipale (compare county seat).
There are not many perfect homonymous Italian municipalities. There are only six cases in 12 comuni: 
- Calliano: Calliano, Piedmont and Calliano, Trentino
- Castro: Castro, Apulia and Castro, Lombardy
- Livo: Livo, Lombardy and Livo, Trentino
- Peglio: Peglio, Lombardy and Peglio, Marche
- Samone: Samone, Piedmont and Samone, Trentino
- San Teodoro: San Teodoro, Sardinia and San Teodoro, Sicily
This is mostly due to the fact the name of the province or region was appended to the name of the municipality in order to avoid the confusion. Remarkably two provincial capitals share the name Reggio: Reggio nell'Emilia, the capital of the province of Reggio Emilia, in the Emilia-Romagna, and Reggio di Calabria, the capital of the homonymous metropolitan city. Many other towns or villages are likewise partial homonyms (e.g. Anzola dell'Emilia and Anzola d'Ossola, or Bagnara Calabra and Bagnara di Romagna).
- Communes of France
- Municipio, Spanish & Portuguese
- Medieval commune
- Municipalities of Switzerland - those in Italian speaking areas of the country are called comuni