Which satellite system is used for global positioning (GPS)?

The Global Positioning System (GPS) is a satellite-based navigation network developed and operated by the United States Department of Defense. It consists of at least 24 active satellites orbiting Earth in six orbital planes. Each satellite transmits radio signals that are received by GPS devices on the ground. By calculating the time it takes for the signals to travel, the receiver determines precise location, speed, and time. GPS is used in aviation, navigation, defense, and daily life applications like smartphones and mapping. Other nations also operate similar systems, including GLONASS (Russia), Galileo (Europe), and NavIC (India).