A naval ship (or naval vessel) is a militaryship (or sometimes boat, depending on classification) used by a navy. Naval ships are differentiated from civilian ships by construction and purpose. Generally, naval ships are damage resilient and armed with weapon systems, though armament on troop transports is light or non-existent.
Naval ship classification is a field that has changed over time, and is not an area of wide international agreement, so this article currently uses the system as currently used by the United States Navy.
Aircraft carrier – ships that serve as mobile seaborne airfields, designed primarily for the purpose of conducting combat operations by Carrier-based aircraft which engage in attacks against airborne, surface, sub-surface and shore targets.
Submarine – self-propelled submersible types regardless of whether they are employed as combatant, auxiliary, or research and development vehicles which have at least a residual combat capability.
Patrol combatant – combatants whose mission may extend beyond coastal duties and whose characteristics include adequate endurance and sea keeping providing a capability for operations exceeding 48 hours on the high seas without support.
Amphibious warfare – ships having organic capability for amphibious assault and which have characteristics enabling long duration operations on the high seas.
Combat logistics – ships that have the capability to provide underway replenishment to fleet units.
Mine warfare – ships whose primary function is mine warfare on the high seas.
Coastal defense – ships whose primary function is coastal patrol and interdiction.
Sealift – ships that have the capability to provide direct material support to other deployed units operating far from home base.
Support – ships, such as oilers and auxiliary ships designed to operate in the open ocean in a variety of sea states to provide general support to either combatant forces or shore based establishments. (Includes smaller auxiliaries which, by the nature of their duties, leave inshore waters).
Service type craft – navy-subordinated craft (including non-self-propelled) designed to provide general support to either combatant forces or shore-based establishments.
In rough order of tonnage (largest to smallest), modern surface naval ships are commonly divided into the following different classes. The larger ships in the list can also be classed as capital ships.
Some classes above may now be considered obsolete as no ships matching the class are in current service. There is also much blurring and gray areas between the classes, depending on their intended use, history, and interpretation of the class by different navies.
Training ship are ships to train students into sailors. Sail training ships are used to provide an unconventional and effective way of building many useful skills on and off the water.
Torpedo trials craft are ships used by navies for the development of new naval torpedoes and during practice firings. These craft are designed to track and monitor, locate and retrieve the spent torpedo for analysis and refurbishment for reuse.
Repair ships are ships to provide maintenance and repairs to warships.