A bearing is a cylindrical piece of machinery that functions to reduce friction between two flat surfaces in contact. Within aircraft, bearings function to hold journals and rods in place and absorb shock during machine operations and landings. They work to prevent damage from heat and pressure by reducing friction between two points of contact. Bearings also serve the purpose of protecting vital components of aircraft, including engines, actuators, and missile launchers by allowing for greater mobility (sometimes a full 360 degrees). The part of machinery that needs bearing support is inserted into the circular opening of the bearing, and the bearing rotates around it.