A computer is
an electronic device that processes data and converts it into information that people can use.
Moore's Law. Moore predicted that the number of transistors in computer circuits would double every couple of years. As it turns out, his prediction has been fairly accurate.
or electronic commerce, is the buying and selling of products and services over the Internet.
personal computer (PC)
is used by one person at a time. Desktop and laptop computers, MP3 players, and personal digital assistants (PDAs) are all examples of PCs, which are also called microcomputers.
personal digital assistant (PDA) is a computer that
is small enough to hold in one's hand. With PDAs, people can track appointments, store addresses, and keep notes.
used by several people, even up to hundreds of people at once. These computers are used in small- to medium-sized organizations, such as schools, hospitals, hotel chains, banks, and churches.
or supercomputer, is large enough to fill several rooms. These computers are used by thousands of people at the same time in organizations such as government agencies.