In a two-dimensional coordinate system, an azimuth is the direction to a target or other reference point. The azimuth may be relative to the position of the observer, or referred to a standard such as north. If the coordinate system is geographic, north has a value of zero angular units.
In three-dimensional coordinate systems, azimuth is coupled to range to define a path (e.g., flight path or projectile trajectory).
Different systems of angular measurement are used for different applications of azimuth. For example, in conventional navigation, azimuths are stated in degrees. When an artillery forward observer calls for fire using azimuths, the units are mils.