The entry visa is the authorization granted to non-EU foreign citizens (belonging to countries outside the European Union and the Schengen area) for access, transit or stay in Italy.
The visa is issued by the Italian Embassies and Consulates in the territory of residence of the foreign citizen. The list of Italian Embassies and Consulates can be viewed at the following link: La rete diplomatica
The citizens of some countries are exempt from the visa requirement for stays not exceeding 90 days (every 180 days) in the territory of the Schengen countries, including Italy (list at the Farnesina website).
For all long-term stays (over 90 days), the foreigner must always have a visa.
In case of stays longer than three months, and in any case in case they are in possession of a D-type visa, non-EU foreign citizens must apply for a residence permit within 8 working days from their entry in Italy.
The requirements and procedures for issuing the visa are indicated by a special provision, published annually by the MIUR, in agreement with the MAECI and the Ministry of the Interior.
For all the details on issuing visas for Italy: http://vistoperitalia.esteri.it/home/it