In serial communications, where each Bit of the message is transmitted in sequence, stop Bits are extra "1" Bits which follow the data and any parityBit. They mark the end of a unit of transmission (normally a byte or character). For example, characters on an EIA-232serial line may have one or two stop Bits added. Some UARTs even allow for 1.5 stop Bits but one is probably the most commonly used. A serial connection may be described as, for example, "8N1" which means eight data Bits, no parity and one stop Bit. (1995-01-24)