Position fixing is the branch of navigation

Navigation

Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...

 concerned with the use of a variety of visual and electronic

Electronics

Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...

 methods to determine the position of a ship

Ship

Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

, aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 or person on the surface of the Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

.

These techniques include:

• Position line
  Position line
  A position line is a line that can be identified both on a nautical chart or aeronautical chart and by observation out on the surface of the earth...
  
  s and position circle
  Position circle
  A position circle is a circle that can be measured both from a chart and from the surface of the earth for the purpose of position fixing. The circles can be measured by sextant. Two overlapping position circles can be used to give a position fix.-See also:...
  
  s
• Celestial navigation
  Celestial navigation
  Celestial navigation, also known as astronavigation, is a position fixing technique that has evolved over several thousand years to help sailors cross oceans without having to rely on estimated calculations, or dead reckoning, to know their position...
  
  
• Radio navigation
  Radio navigation
  Radio navigation or radionavigation is the application of radio frequencies to determine a position on the Earth. Like radiolocation, it is a type of radiodetermination.The basic principles are measurements from/to electric beacons, especially...
  
  
• Satellite navigation system

Positions may be expressed as a bearing and range from a known landmark or as an angle

Angle

In geometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle.Angles are usually presumed to be in a Euclidean plane with the circle taken for standard with regard to direction. In fact, an angle is frequently viewed as a measure of an circular arc...

s of latitude

Latitude

In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

 and longitude

Longitude

Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

 relative to a map datum.

Generally speaking a position fix is calculated by taking into account measurements (referred to as observations) of distances or angles to reference points whose positions are known.