A computer system includes a computer, peripheral(外围的)devices, and software. The electric(电气的), electronic, and mechanical(机械的) devices used for processing data are referred to as hardware. In addition to the computer itself, the term “hardware” refers to components called peripheral devices that expand(扩展) the computer’s input, output, and storage capabilities. Computer hardware in and of itself (本身)does not provide a particularly useful mind(意识) tool. To be useful, a computer requires a set of instructions, called software or a computer program, which tells the computer how to perform a particular task. Computers become even more effective when connected to other computers in a network so users can share information.