Are you new to computers? Do you wonder what they do and  why you would want to use one? Welcome—you're in the right place. This  article gives an overview of computers: what they are, the different  types, and what you can do with them.
What are computers?
Computers are machines that perform tasks or calculations according to a set of instructions, or programs.  The first fully electronic computers, introduced in the 1940s, were  huge machines that required teams of people to operate. Compared to  those early machines, today's computers are amazing. Not only are they  thousands of times faster, they can fit on your desk, in your lap, or  even in your pocket.
Computers work through an interaction of hardware and software. Hardware  refers to the parts of a computer that you can see and touch, including  the case and everything inside it. The most important piece of hardware  is a tiny rectangular chip inside your computer called the central processing unit (CPU), or microprocessor.  It's the "brain" of your computer—the part that translates instructions  and performs calculations. Hardware items such as your monitor,  keyboard, mouse, printer, and other items are often called hardware devices, or devices.
           Software refers to the  instructions, or programs, that tell the hardware what to do. A word  processing program that you can use to write letters on your computer is  a type of software. The operating system (OS) is software that manages  your computer and the devices connected to it. Two well-known operating  systems are Windows and  Macintosh operating system. Your computer uses the Windows operating system.
Types of computers
Computers range in size and capability. At one end of the scale are supercomputers,  very large computers with thousands of linked microprocessors that  perform extremely complex calculations. At the other end are tiny  computers embedded in cars, TVs, stereo systems, calculators, and  appliances. These computers are built to perform a limited number of  tasks.
The personal computer, or PC,  is designed to be used by one person at a time. This section describes  the various kinds of personal computers: desktops, laptops, handheld  computers, and Tablet PCs.
Desktop computers
               Desktop computers are  designed for use at a desk or table. They are typically larger and more  powerful than other types of personal computers. Desktop computers are  made up of separate components. The main component, called the system unit,  is usually a rectangular case that sits on or underneath a desk. Other  components, such as the monitor, mouse, and keyboard, connect to the  system unit.
Laptop computers
               Laptop computers are lightweight mobile PCs with a thin screen. They are often called notebook computers  because of their small size. Laptops can operate on batteries, so you  can take them anywhere. Unlike desktops, laptops combine the CPU,  screen, and keyboard in a single case. The screen folds down onto the  keyboard when not in use.
Handheld computers
               Handheld computers, also called personal digital assistants (PDAs),  are battery-powered computers small enough to carry almost anywhere.  Although not as powerful as desktops or laptops, handhelds are useful  for scheduling appointments, storing addresses and phone numbers, and  playing games. Some have more advanced capabilities, such as making  telephone calls or accessing the Internet. Instead of keyboards,  handhelds have touch screens that you use with your finger or a stylus (a pen-shaped pointing tool).
Tablet PCs
               Tablet PCs are mobile PCs  that combine features of laptops and handhelds. Like laptops, they're  powerful and have a built-in screen. Like handhelds, they allow you to  write notes or draw pictures on the screen, usually with a tablet pen  instead of a stylus. They can also convert your handwriting into typed  text. Some Tablet PCs are “convertibles” with a screen that swivels and  unfolds to reveal a keyboard underneath.
What can you do with computers?
In the workplace, many people use computers to  keep records, analyze data, do research, and manage projects. At home,  you can use computers to find information, store pictures and music,  track finances, play games, and communicate with others—and those are  just a few of the possibilities.
You can also use your computer to connect to the Internet,  a network that links computers around the world. Internet access is  available for a monthly fee in most urban areas, and increasingly, in  less populated areas. With Internet access, you can communicate with  people all over the world and find a vast amount of information.
Here are some of the most popular things to do with computers:
The web
The World Wide Web (usually called the Web, or web)  is a gigantic storehouse of information. The web is the most popular  part of the Internet, partly because it displays most information in a  visually appealing format. Headlines, text, and pictures can be combined  on a single webpage—much like a page in a magazine—along with sounds and animation. A website is a collection of interconnected webpages. The web contains millions of websites and billions of webpages.
               Surfing the web means  exploring it. You can find information on the web about almost any topic  imaginable. For example, you can read news stories and movie reviews,  check airline schedules, see street maps, get the weather forecast for  your city, or research a health condition. Most companies, government  agencies, museums, and libraries have websites with information about  their products, services, or collections. Reference sources, such as  dictionaries and encyclopedias, are also widely available.
The web is also a shopper's delight. You can  browse and purchase products—books, music, toys, clothing, electronics,  and much more—at the websites of major retailers. You can also buy and  sell used items through websites that use auction-style bidding.
E‑mail
               E‑mail (short for electronic mail)  is a convenient way to communicate with others. When you send an e‑mail  message, it arrives almost instantly in the recipient's e‑mail inbox.  You can send e‑mail to many people simultaneously, and you can save,  print, and forward e‑mail to others. You can send almost any type of  file in an e‑mail message, including documents, pictures, and music  files. And with e‑mail, you don't need a stamp! 
Instant messaging
Instant messaging is like having a real-time  conversation with another person or a group of people. When you type  and send an instant message, the message is immediately visible to all  participants. Unlike e‑mail, all participants have to be online  (connected to the Internet) and in front of their computers at the same  time. Communicating by means of instant messaging is called chatting.
Pictures, music, and movies
If you have a digital camera, you can move  your pictures from the camera to your computer. Then you can print them,  create slide shows, or share them with others by e‑mail or by posting  them on a website. (To learn more about what you can do with photos, see  Working with digital pictures .) You  can also listen to music on your computer, either by importing  (transferring to your computer) music from audio CDs or by purchasing  songs from a music website. Or, tune in to one of the thousands of radio  stations that broadcast over the Internet. If your computer comes with a  DVD player, you can watch movies.





 
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