1.1 DATA COMMUNICATIONS
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 (tele
is Greek for "far"). The word data refers to information presented in whatever form is
agreed upon by the 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.