Serial transmission is a method of sending data one bit at a time over a single channel or wire. This technique is commonly used in communication between devices, such as computers and peripherals, because it simplifies the wiring and reduces costs. In contrast to parallel transmission, which sends multiple bits simultaneously, serial transmission is often slower but more reliable over long distances. It is widely used in various applications, including USB connections and RS-232 serial ports, making it a fundamental concept in data communication.