In navigation, bearing is the horizontal angle between the direction of an object and another object, or between it and that of true north.
Absolute bearing refers to the angle between the magnetic north (magnetic bearing) or true north (true bearing) and an object. For example, an object to the East would have an absolute bearing of 90 degrees.
Relative bearing refers to the angle between the craft's forward direction and the location of another object. For example, an object relative bearing of 0 degrees would be dead ahead; an object relative bearing 180 degrees would be behind. Bearings can be measured in mils or degrees.