The USB to serial adapter has a USB-A port on one end and a serial port on the other. The serial port is most commonly RS232, which is a standard that dates back to the 1960s.

Before USB ports became standard on PCs, several devices connected through a serial port. They're obsolete in many ways, but they still see some use.

The USB to serial adapter has a USB-A port on one end and a serial port on the other. The serial port is most commonly RS232, which is a standard that dates back to the 1960s.