The Imperial War Museum covers both service and civilian aspects of war. The extensive collections include a range of vehicles from both sides of the world wars. Representing World War I are a British Mark V tank and a Sopwith Camel fighter. An American Sherman tank is preserved from World War II, as are a British Spitfire Mark I, a German Heinkel He 162 jet fighter, and a German V-1 flying bomb (V-1 missile) and V-2 rocket (V-2 missile). More aircraft are exhibited at Duxford airfield, a branch museum near Cambridge, where the American Air Museum in Britain, designed by Sir Norman Foster and opened in 1997, is situated. Other branch museums include a World War II-era cruiser, HMS Belfast, moored in the River Thames near the Tower of London, and the Cabinet War Rooms used by Winston Churchill, located on King Charles Street, London.

The museum holds an extensive photographic archive and has an outstanding art collection, containing works by Paul Nash (Nash, Paul), Laura Knight, John Piper, Sir Stanley Spencer (Spencer, Sir Stanley), Norman Wilkinson, and many others.

The visitor to the museum is presented with a number of realistic audiovisual, interactive, and other simulated experiences. These include a walk through a frontline trench at the Somme (Somme, First Battle of the) in 1916, the devastation of a London street bombed in 1940, a flight simulator, and a video representation of a nuclear explosion. The museum also holds special exhibitions.