Serial communications

In telecommunications and computer science, serial communications is the process of sending data one bit at one time, sequentially, over a communications channel or computer bus. This is in contrast to parallel communications, where all the bits of each symbol are sent together. Serial communications is used for all long-haul communications and most computer networks, where the cost of cable and synchronization difficulties make parallel communications impractical. Serial computer buses are becoming more common as improved technology enables them to transfer data at higher speeds.
See more at Wikipedia.org...

UART