4. There are two methods of data transmission – serial and parallel. Explain the difference between them.

Serial Data Transmission is the process of sending data one bit at a time, in a sequence, over a communication channel.
Parallel Data Transmission is the process of sending several data signals simultaneously over several parallel channels.

The difference between a parallel and a serial data transmission is that serial transmission sends data one bit/data at a time, while parallel transmission sends multiple bits/data in the same time. Also, serial transmission uses only one communication channel while parallel transmission uses multiple communication channels.