GPS stands for Global Positioning System. It is a space-based navigation system consisting of 24 satellites that orbit Earth and provide location and time information to GPS receivers. GPS uses trilateration to calculate the user's precise location by timing the signals sent by GPS satellites high above. Common applications of GPS include its use by hikers and vehicles for navigation purposes. However, a con of in-vehicle GPS is that it can be expensive and the talking voices used for directions can become annoying.