What Is a Computer?

A computer is a device that can perform computations and make logical decisions billions of times faster than human beings can. For example, many of today’s personal computers can perform several billion additions per second. A person could operate a desk calculator for an entire lifetime and still not complete as many calculations as a powerful personal computer can perform in one second! (Points to ponder: How would you know whether the person added the numbers correctly? How would you know whether the computer added the numbers correctly?) Today’s fastest supercomputers can perform trillions of ad- ditions per second!

Computers process data under the control of sets of instructions called computer pro- grams. These programs guide the computer through orderly sets of actions specified by people called computer programmers.

A computer consists of various devices referred to as hardware (e.g., the keyboard, screen, mouse, hard disk, memory, DVD drives and processing units). The programs that run on a computer are referred to as software*.* Hardware costs have been declining dramat- ically in recent years, to the point that personal computers have become a commodity. In this book, you’ll learn proven methods that are reducing software development costs— object-oriented programming and object-oriented design.