La piraterie désigne une forme de banditisme pratiquée sur mer par des marins appelés pirates. Cependant, les pirates ne se limitent pas seulement aux pillages de navire, et attaquent parfois de petites villes côtières.

Piracy is an act of robbery or criminal violence at sea. Those who engage in acts of piracy are called pirates. The earliest documented instances of piracy were in the 14th century BC, when the Sea Peoples, a group of ocean raiders, attacked the ships of the Aegean and Mediterranean civilizations. Narrow channels which funnel shipping into predictable routes have long created opportunities for piracy, as well as for privateering and commerce raiding. Privateering uses similar methods to piracy, but the captain acts under orders of the state authorizing the capture of merchant ships belonging to an enemy nation, making it a legitimate form of war-like activity by non-state actors.(For a land-based parallel, compare the association of bandits and brigands with mountain passes.) Historic examples include the waters of Gibraltar, the Strait of Malacca, Madagascar, the Gulf of Aden, and the English Channel, whose geographic strictures facilitated pirate attacks.