Marines (or naval infantry) are military personnel generally trained to operate on both land and sea, with a particular focus on amphibious warfare. Historically, the main tasks undertaken by marines have included raiding ashore (often in support of naval objectives) and the boarding of vessels during ship-to-ship combat or capture of prize ships. Marines also assisted in maintaining security, discipline, and order aboard ships (reflecting the historically pressed-nature of the rest of the ship's company and the risk of mutiny). While maintaining many of their historical roles, in modern times, marines also engage in duties including rapid-response operations, humanitarian aid, disaster relief, special operations roles, and counter-terrorism operations. In most nations, marines are an integral part of that state's navy, such as the United Kingdom's Royal Marines or Russia's Naval Infantry; in some countries their marine forces can instead be part of the land army, such as the French Troupes de marine, or, more uncommonly, a nation’s marine forces may be an independent military branch such as the United States Marine Corps or the Ukrainian Marine Corps.
The exact term "marine" is not found in many languages other than English. In French-speaking countries, two terms which could be translated as "marine", but do not translate exactly: troupes de marine (marine troops) and fusiliers-marins (marine riflemen) and fuzileiros navais in Portuguese (lit. 'Naval fusiliers'). The word marine means "navy" in many European languages such as Dutch, French, German, Italian and Norwegian. “Naval infantry” may also refer to sailors forming both temporary and permanent infantry units, such as the British WWI-era 63rd (Royal Naval) Division (an infantry division made-up of Royal Navy sailors and Royal Marines on a semi-permanent basis) or the Imperial Japanese Naval Landing Forces (ad-hoc formations of Imperial Japanese Navy sailors temporarily pressed into service as infantry).
