1. Message Message is the information to be communicated. The message may consist of text, numbers, pictures etc.
2. Sender Sender is a device that sends the message. Normally, computer is used as sender in data communication systems. It is also called source or transmitter.
3. Medium Medium is the physical path that connects sender and receiver. It is used to transmit data. The medium can be a copper wire, a fiber optic cable, microwaves etc.
4. Receiver Receiver is a device that receives message. It is also called sink. The receiver can be computer, printer, or another computer related device. It must be proficient of accommodating the message.
5. Protocol A protocol is a set of policies that administrates data communication. It represents an agreement between communication devices. Devices cannot communicate without protocol.