A computer is an electronic device that performs various functions including problem-solving, communication, education, and entertainment based on user instructions. Computers can be classified by application (analog, digital, hybrid) and size (micro, mini, mainframe, supercomputers), and consist of hardware and software components. The document outlines various computer uses in fields like banking, education, and healthcare, and explains types of software including operating systems and applications, as well as computer networks and their configurations.