Serial communications are preferred over the parallel one when there is the scarcity of available I/O pins. Besides, they are also simple and economical when the distance of communication is long. The embedded-lab.com just posted a tutorial on PIC UART that allows the PIC microcontroller to communicate with a PC through a standard RS232 port. The full duplex mode of asynchronous communication between the PC and PIC is demonstrated.
Tutorial on PIC Serial communication – [Link]