Helicopters are agile aircraft capable of taking off and landing vertically, hovering and flying in different directions.

The lift and thrust of helicopters are provided by spinning rotors, usually featuring two or more blades.

Helicopters typically have one main rotor and one smaller rotor in the tail which counters the torque effect, stopping the helicopter from spinning in the opposite direction.

Some helicopters have two horizontal rotors which spin in opposite directions, allowing the helicopter to lift heavier objects.

Helicopters have advantages over fixed-wing aircraft that allow them to access hard to reach areas, particularly useful in rescue situations.

As well as search and rescue, helicopters are useful for tourism, medical transport, fighting fires, aerial photography, military activity and more.

Helicopters have a number of limitations. They can be noisy, vibrate a lot and aren't as fast as fixed-wing aircraft.

Vertical flight has existed in some form as far back as 400 BC when children in China played with flying toys made from bamboo which created lift when spun.

Around 1480 Leonardo da Vinci designed a machine resembling a helicopter which can be described as an ‘aerial screw’.

The first working helicopter is believed to have been the Focke-Wulf Fw 61, first flown in 1936.

The fastest speed recorded by a helicopter is around 400 kph (248 mph).

The longest distance traveled in a helicopter without landing is 3562 km (2213 miles).

Helicopters can be used to fight fires by carrying tanks or helibuckets filled with water.

Hovering can be the most difficult skill when flying a helicopter. Constant control is required to offset gusty air created by the helicopter.

Small quadcopters are popular among researchers, the military and amateur enthusiasts due to their ease of control and affordable construction.

Helicopters are sometimes called choppers.