What exactly is IT sector, and what do the IT companies do?

IT or Information technology deals with information - its storage, retrieval, usage, processing in relation to a business or similar enterprise or government. It is a complete system of information management using technology and computers and to communicate the same in controlled manner to authorized users appropriately.

IT sector is considered a sub sector of Information and communication sector. It involves computer systems with Hardware, Software, Network, Infrastructure and associated other equipment. Today this also includes, electronics, telecom, internet, semi-conductors and e-commerce and more! IT sector is the industry where people work with computers on imaginable stuff. Employees get highly paid to sit on a chair in front of a computer screen. They are paid for solving highly complex problems and maintaining large scale distributed systems.