Azimuth is an angular measurement that specifies the direction of one point or object relative to another in a horizontal plane. It is one of the basic methods of describing direction in surveying, navigation, astronomy, military operations, geodesy, engineering, and mapping. Instead of using compass directions such as north, northeast, or southwest, an azimuth expresses direction as a single angle measured around a full circle.
By convention, an azimuth is measured clockwise from a reference direction, which is almost always true north or magnetic north, depending on the application. The angle begins at 0\(^{\circ}\) (north) and increases clockwise through 90\(^{\circ}\) (east), 180\(^{\circ}\) (south), 270\(^{\circ}\) (west), and returns to 360\(^{\circ}\), which is identical to 0\(^{\circ}\). Because every possible horizontal direction corresponds to one unique angle between 0\(^{\circ}\) and 360\(^{\circ}\), azimuths eliminate the ambiguity that can occur when using quadrant bearings.
The reference north used for an azimuth depends on the discipline. True azimuth is measured from true (geographic) north, which is the direction toward Earth's geographic North Pole. Magnetic azimuth is measured from magnetic north, the direction indicated by a magnetic compass, and differs from true north by the local magnetic declination. Some engineering and surveying applications also use grid azimuth, which is measured relative to grid north on a map projection rather than true north.
Although the terms azimuth and bearing are sometimes used interchangeably, they are not identical. A bearing is often expressed relative to north or south and then toward east or west (for example, N 35\(^{\circ}\) E), whereas an azimuth is expressed as a single clockwise angle from north (for example, 35\(^{\circ}\)). Every bearing can be converted to an azimuth and vice versa, but azimuths are generally preferred in engineering and computational applications because they provide one continuous angular measurement from 0\(^{\circ}\) to 360\(^{\circ}\). Azimuth measures only horizontal direction. It does not indicate distance, elevation, slope, or vertical angle. To completely specify the location of an object, azimuth is typically combined with additional measurements such as distance, altitude, elevation angle, or geographic coordinates.
