Have you used a computer recently? Chances are you have. If you have made a phone call, watched a TV, played a video game or ridden in a car you have used a computer. Even the text on this page was put into type by a computer. Computers have become important and valuable tools in today's world. Since they affect so many parts of our lives, it is important to be aware of how they are used and how they work. Computers are conformed to follow instructions from humans. They can solve only the problems that people tell them to solve. Since people cannot solve every problem, neither can computers. To tell a computer what to do, you have to know what problem you want to solve and have a plan for solving it. Conventionally a computer consists of some form of memory for data storage, at least one element that carries out arithmetic and logic operations, and a sequencing and control element that can change the order of operations based on the information that is stored. Peripheral devices allow information to be entered from an external source, and allow the results of operations to be sent out. A computer's processing unit executes series of instructions that make it read, manipulate and then store data. Conditional instructions change the sequence of instructions as a function of the current state of the machine or its environment. When purchasing a computer, no matter what choice you make, you can't really go wrong. Today's current model PCs and Macs offer tremendous value and computing horsepower that we could only dream about just a few years back. Even the most inexpensive models can handle any application you throw at them. In other words, they are plenty well-equipped to allow you to write letters, access the Internet, work with digital pictures, play games and do all the other things that most people are interested in doing with a PC. In fact, even advanced applications such as video editing and speech recognition--where you talk to your computer and it converts your spoken words to typed text on the screen--is usually no problem for today's lowest-cost computers. Also, you need to figure out how much you're willing to spend on a PC. Full-blown computer systems are available for around $500 (or even less if you choose to take advantage of rebates and other special offers), but you can also spend $3,000 or more if you really want to. So, as with other big purchases, give yourself a budget range to work within.