A rocket launcher is any device that launches a rocket-propelled projectile, although the term is often used in reference to mechanisms that are portable and capable of being operated by an individual.
Weapon systems that fall into this category include the shoulder-launched missile weapon, the wider international term for any weapon that fires a rocket-propelled projectile at a target, yet is small enough to be carried by a single person, and fired while held on one's shoulder. However, the term bazooka, is also often used for any shoulder-launched rocket weapon. Specific types of rocket launchers within this group include the rocket-propelled grenade, better known as the RPG, which is a type of shoulder-launched anti-tank weapon designed by the Soviet Union; the anti-tank guided missile, a guided missile primarily designed to hit and destroy heavily-armored tanks and other armored fighting vehicles; and the Man-portable air-defense systems, which provides shoulder-launched surface-to-air missiles. A smaller variation is the gyrojet, a small arm rocket launcher with ammunition slightly larger than that of a .45-caliber pistol. Recoilless rifles are sometimes confused with rocket launchers. However, the recoilless rifle merely fires a large-sized bullet-like projectile, and not a projectile that continues to propel itself after leaving the barrel of the weapon.
Larger-scale devices which serve to launch rockets include the multiple rocket launcher, a type of unguided rocket artillery system; the transporter erector launcher, a vehicle with an integrated prime mover that can carry, elevate to firing position and launch one or more missiles and various launchers for guided missiles, including ones for surface-to-air missiles, anti-ship missiles, and antisubmarine warfare guided missiles (see ASROC, Sea Lance, etc.)
The largest scale currently existing device that can be considered a rocket launcher is the launch pad, the area and facilities where rockets or spacecraft liftoff. However, the launch pad itself is more of a platform, and serve only a minimal role in aiming or controlling the path of the launched object.