The Polizia i Stato (State Police or PdS) is one of the national police forces of Italy. It is responsible for providing general police duties in Italy; patrolling motorways (autostrada), railways, airports, customs (together with the Guardia di Finanza) as well as certain waterways, and assisting the local police forces. The Polizia di Stato is a civil police force, but it is militarily organized. This does not mean that it is a military institution, but its structure is based on the military. The Polizia di Stato is the principal Italian police force for the maintenance of public security (since it is run directly from the Dipartimento della Pubblica Sicurezza (Department of Public Security), and the keeping of public order. It is a civil police force in contrast to the other main police forces of Italy, the Carabinieri, which is a military police (gendarmerie) force and the Guardia di Finanza, the Italian customs and border protection police that also falls in the military corps category.