Relationship between communication device and
transmission media.

Communication systems are electronic systems that transmit data from one location to another. Whether wired or wireless, every communication system has four basic elements :

1. Sending and receiving devices :
   
   • Sending devices – A device that initiates an data, instructions and information. These are often a computer.
   • Receiving devices – A device that accepts an data, instructions and information. These are often a computer.
2. Communication channel / Transmission media :
   Medium that carries the message ( data, instructions and information).
3. Connection devices :
   This devices act as an interface between the sending and receiving devices and the communication channel. They convert outgoing messages into packets that can travel across the communication channel. Each packet contains the data, as well as the recipient, the sender, and the sequence information used to reassemble (used protocol ) the data at the destination.
4. Protocol is a set of rules that govern data communication.
   Example : TCP/IP – Transmission Control Protocol / Internet Protocol.