GPS; stands for "Global Positioning System". GPS devices are only receivers; they do not transmit any signals. GPS receivers calculate their own position, speed and course by receiving the GPS signals from various satellites and converting the signals to meaningful digital messages. Nowadays; there are numerous type of GPS receivers; some with screen and maps; some for sporting / hiking purposes; some for use with industrial machines and some for use with laptop / PC computers. Laptop / PC GPS devices might have a usb cable connection with the PC as well as having Bluetooth connections. These GPS receivers are commonly named after "USB GPS", "Bluetooth GPS" or "Mouse GPS".
These portable PC GPS receivers are very useful for having their own internal antenna and having the power from the USB connection of the PC. They're also usually marine-proof; performing well under heavy weather / marine conditions. (Usually IPX7 environmental protection is used)