In Italy there are not as many university dormitories or boarding schools as in Austria or Germany (with the exception of Trento), so many students try to find a room to rent. Another Italian "peculiarity" is double rooms, where only one bed is rented in a double room.
Many offers can be found online on the buying and selling platforms or on the notice boards of the faculties of the respective universities. You can also find ads on Facebook, in groups dedicated to this purpose.
Since many apartments are rented illegally, a law has been passed that provides tax advantages for student tenants (art. 14 431/98). It is worthwhile to stipulate a regular contract!
List of useful websites:
Heimverzeichnis italienischer Universitäten: www.studenti.it
Opera universitaria di Trento: www.operauni.tn.it (Heimplätze)
Posti alloggio: www.google.it - "opera universitaria + città + alloggio"