A positioning system is a system for determining the position of an object in space. Positioning system technologies exist ranging from interplanetary coverage with meter accuracy to workspace and laboratory coverage with sub-millimeter accuracy. A major subclass is made of geopositioning systems, used for determining an object's position with respect to Earth, i.e., its geographical position; one of the most well-known and commonly used geopositioning systems is the Global Positioning System (GPS) and similar global navigation satellite systems (GNSS).

Interplanetary-radio communication systems not only communicate with spacecraft, but they are also used to determine their position. Radar can track targets near the Earth, but spacecraft in deep space must have a working transponder on board to echo a radio signal back. Orientation information can be obtained using star trackers.

Global navigation satellite systems (GNSS) allow specialized radio receivers to determine their 3-D space position, as well as time, with an accuracy of 2–20 metres or tens of nanoseconds. Currently deployed systems use microwave signals that can only be received reliably outdoors and that cover most of Earth's surface, as well as near-Earth space.

The existing and planned systems are:

Networks of land-based positioning transmitters allow specialized radio receivers to determine their 2-D position on the surface of the Earth. They are generally less accurate than GNSS because their signals are not entirely restricted to line-of-sight propagation, and they have only regional coverage. However, they remain useful for special purposes and as a backup where their signals are more reliably received, including underground and indoors, and receivers can be built that consume very low battery power. LORAN is an example of such a system.

A local positioning system (LPS) is a navigation system that provides location information in all weather, anywhere within the coverage of the network, where there is an unobstructed line of sight to three or more signaling beacons of which the exact position on Earth is known.

Unlike GPS or other global navigation satellite systems, local positioning systems don't provide global coverage. Instead, they use beacons, which have a limited range, hence requiring the user to be near these. Beacons include cellular base stations, Wi-Fi and LiFi access points, and radio broadcast towers.

In the past, long-range LPS's have been used for navigation of ships and aircraft. Examples are the Decca Navigator System and LORAN. Nowadays, local positioning systems are often used as complementary (and in some cases alternative) positioning technology to GPS, especially in areas where GPS does not reach or is weak, for example, inside buildings, or urban canyons. Local positioning using cellular and broadcast towers can be used on cell phones that do not have a GPS receiver. Even if the phone has a GPS receiver, battery life will be extended if cell tower location accuracy is sufficient. They are also used in trackless amusement rides like Pooh's Hunny Hunt and Mystic Manor.