A USB Modem NEMA Port driver is typically used when a USB modem or GPS receiver device (or similar communication equipment) connects to a Windows computer via a USB port. "NEMA" is likely a typo or abbreviation for NMEA (National Marine Electronics Association), which is a standard for communication between devices like GPS receivers and computers. These devices may use a virtual COM port (also referred to as NEMA or NMEA ports) to communicate with software applications.

In this context, the driver allows Windows to properly interface with the modem or GPS receiver by mapping it to a serial port (COM port) for data transmission.