Having a RS-232 serial port on a PC can be very useful when working with microcontroller boards and other embedded systems. It allows the PC to send information to the board and receive information from it. This can also be used when debugging a board.
Modern laptop computers no longer come with fixed RS-232 ports. The solution to this is to add a RS-232 port by using a USB to RS-232 converter cable such as the US232R cable from FTDI Chip.
This article on installing the drivers for an FTDI Chip USB to serial port converter cable shows how to install drivers for the cable on a Windows 8 PC.