Business data communications and networking are among the most rapidly evolving technologies in our society today. One of the consequences of this expansion is a huge increase in the number of occupations where the expertise of these technologies is required for success. Business data communications and networking are changing the way we work and live. Business choices must be made faster than ever before, and decision-makers must have rapid access to correct information. The transfer of digital data between two or more computers is referred to as data communications, and a computer network or data network is a telecommunications network that allows computers to exchange data. It enables enterprises to cut costs and increase productivity by sharing data and common equipment among several PC. At the same time, the network may be connected through cables, telephone lines, or infrared beams, which is less expensive and helps to cut costs.