A serial port is a physical interface through which data is transferred (uni- or bidirectionally) one bit at a time. Largely superseded in the consumer market by USB, serial connections are still commonly used in many other specialist applications. Typical applications include scientific/medical instruments, industrial controllers and server diagnostics...

A serial port is a physical interface through which data is transferred (uni- or bidirectionally) one bit at a time. Largely superseded in the consumer market by USB, serial connections are still commonly used in many other specialist applications. Typical applications include scientific/medical instruments, industrial controllers and server diagnostics.

More information at http://en.wikipedia.org/wiki/Serial_port