What is Data Communication

          When we communicate, we are sharing information. This sharing can be local or remote. Between individuals, local communication usually occurs face to face, while remote communication takes place over distance. The term telecommunication, which  includes telephony, telegraphy, and television, means communication at a distance (teleis Greek for "far").
          The word data refers to information presented in whatever form is agreed upon bythe parties creating and using the data.
          Data communications are the exchange of data between two devices via some form of transmission medium such as a wire cable. For data communications to occur, the communicating devices must be part of a communication system made up of a combination of hardware (physical equipment) and software (programs). The effectiveness of a data communications system depends on four fundamental characteristics: delivery, accuracy, timeliness, and jitter.