In military terminology, a cruiser is a large warship capable of engaging multiple targets simultaneously.
Modern United States Navy guided missile cruisers (CG and CGN hull classification symbols) perform primarily in a Battle Force role. These ships are multi-mission -- anti-aircraft (AAW), anti-submarine (ASW), and anti-surface (ASUW) surface combatants capable of supporting carrier battle groups, amphibious forces, or of operating independently and as flagships of surface action groups.
Technological advances in surface-to-air missiles coupled with the AEGIS combat system have increased cruisers' AAW capability, while Tomahawk missiles give them long-range strike mission capability. These weapon systems have restored an offensive strike role to the surface forces that seemed to have been lost to air power at Pearl Harbor.
All cruisers currently in commission in the US Navy are members of the Ticonderoga class.