The Ranger School is a 62-day United States Army small unit tactics and leadership course that develops functional skills directly related to units whose mission is to engage the enemy in close combat and direct fire battles. Ranger training was established in September 1950 at Fort Benning, Georgia. The Ranger course has changed little since its inception. Since 1995, it was an eight-week course divided into three phases. The 62 day course of instruction is divided into three phases: Darby Phase, Mountain Phase, and Swamp Phase.

The Ranger School is open to U.S. military personnel from the Army, Marine Corps, Navy, Air Force, and Space Force, as well as selected students from other nations allied with the United States. The course is conducted in various locations. Benning Phase occurs in and around Camp Rogers and Camp Darby at Fort Benning, Georgia. Mountain Phase is conducted at Camp Merrill, in the remote mountains near Dahlonega, Georgia. Swamp Phase is conducted in the coastal swamps at various locations near Camp Rudder, Eglin Air Force Base in Florida.^{[citation needed]}

The school is not organizationally affiliated with the 75th Ranger Regiment. Ranger School falls under control of the United States Army Training and Doctrine Command as a school open to most members of the United States Army, but the 75th Ranger Regiment is a Special Operations warfighting unit organized under the United States Army Special Operations Command. The two share a common heritage and subordinate battalions common lineage, and Ranger School is a requirement for all officers and non-commissioned officers (NCO) of the 75th Ranger Regiment.

Those graduating from Ranger School are presented with the Ranger Tab, which is worn on the upper shoulder of the left sleeve of a military uniform, according to U.S. Army regulations. Wearing the tab is permitted for the remainder of a soldier's military career. The cloth version of the tab is worn on the Army Combat Uniform and Army Green Service Uniform; a smaller, metal version is worn on the Army Service Uniform.

"Without a doubt, Ranger School is the most physically and mentally demanding course in the U.S. Army."

Ranger Training had begun in September 1950 at Fort Benning Georgia "with the formation and training of 17 Airborne Companies by the Ranger Training Command". The first class graduated from Ranger training in November 1950, becoming the 1st Ranger Infantry Company. The United States Army's Infantry School officially established the Ranger Department in December 1951. Under the Ranger Department, the first Ranger School Class was conducted in January–March 1952, with a graduation date of 1 March 1952. Its duration was 59 days. At the time, Ranger training was voluntary.

In 1966, a panel headed by General Ralph E. Haines Jr. recommended making Ranger training mandatory for all Regular Army officers upon commissioning. On 16 August 1966, the Chief of Staff of the Army, General Harold K. Johnson, directed it so. This policy was implemented in July 1967. It was rescinded on 21 June 1972 by General William Westmoreland. Once again, Ranger training was voluntary.

In August 1987, the Ranger Department was split from the Infantry School and the Ranger Training Brigade was established. The Ranger Companies that made up the Ranger Department became the current training units—the 4th, 5th and 6th Ranger Training Battalions.