Helicopters are rotorcraft that achieve lift and propulsion through one or more horizontal rotors. Unlike fixed-wing aircraft, which rely on wings to generate lift, helicopters use rotating blades to create vertical lift, allowing them to hover, take off, and land vertically. This capability enables them to access areas that are difficult for other aircraft to reach, such as remote or rugged terrains, and to perform various functions including transportation, search and rescue, medical evacuations, law enforcement, and military operations. Helicopters can have a wide range of designs, including single-rotor configurations with a tail rotor for stability or tandem rotor configurations with two sets of blades. Their versatility and ability to maneuver in tight spaces make them valuable for both civilian and military applications.