Rangers, in the U.S. Army, are elite light infantry units, which operate in uniform, but often behind enemy lines. In the modern U.S. Special Operations Command, the 75th Ranger Regiment conducts raids and also provides a perimeter for operations of the Joint Special Operations Command.
They consider their lineage older than that of the nation; "Rogers' Rangers", of the French and Indian War, was the first American unit to have the Ranger designation. MAJ Robert Rogers' tactical rules are still largely valid and are memorized by Rangers.
More modern Ranger units were organized, in battalion strength, in the Second World War. They were used for high-risk operations such as scaling a cliff to seize a German artillery position at the Battle of Normandy.
Ranger companies were created during the Korean War, but tended to be used as emergency reserves rather than on classic Ranger raiding.