A Personal Navigation Assistant (PNA) also known as Personal Navigation Device or Portable Navigation Device (PND) is a portable electronic product which combines a positioning capability (such as GPS) and navigation functions.
Some PNA devices are PDAs with limited features and can be unlocked.
A satellite navigation device, also called a satnav device or GPS device, uses satellites of the Global Positioning System (GPS) or similar global navigation satellite systems (GNSS) to determine the user's geographic coordinates. It may also display the user's position on a map and offer routing directions (as in turn-by-turn navigation).
As of 2023, four GNSS systems are operational: the original United States' GPS, the European Union's Galileo, Russia's GLONASS, and China's BeiDou Navigation Satellite System. The Indian Regional Navigation Satellite System (IRNSS) will follow and Japan's Quasi-Zenith Satellite System (QZSS) scheduled for 2023 will augment the accuracy of a number of GNSS.