It is unavoidable to be technical when describing how GPS works. It is a radio-navigation system consisting of 24 satellites orbiting the earth, and their respective ground stations. To calculate a position, these satellites serve as reference points when calculating positions relative to a matter of meters.
In other words, GPS triangulates the position of a satellite, its ground station and the area you want to locate. However, this is done in a more scientific and finite measurement of travel time, distance, signal experiences, and atmospheric delays.
To measure GPS points, you must use a GPS receiver that calculates its position by the signals transmitted to the satellites. These satellites send messages containing information such as the time the message was sent and the satellites orbital information. Once it receives this information, the GPS receiver will then measure the transit time of the sent message and calculate the distance of the GPS receiver to the each of the satellites.
The location is then displayed through GPS maps.