Introduction to Computers

In this article

  What are computers?

  Types of computers 

  What can you do with computers? 

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 components 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 Mac OS. Your computer uses the Windows operating system.

      ENIAC
      Introduced in 1946, ENIAC (Electronic Numerical Integrator and Computer) 
      was the first general-purpose electronic computer. It was built for the 
      United States military to calculate the paths of artillery shells. 
      Physically, ENIAC was enormous, weighing more than 27,000 kilograms 
      (60,000 pounds) and filling a large room. To process data, ENIAC used 
      about 18,000 vacuum tubes, each the size of a small light bulb. The tubes 
      burned out easily and had to be constantly replaced.

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.

For information about how to explore the Internet and the web, see Exploring the 
Internet.

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! See Getting started with e-mail.

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.

Gaming

Do you like to play games? Thousands of computer games in every conceivable 
category are available to entertain you. Get behind the wheel of a race car, 
battle frightening creatures in a dungeon, or control civilizations and empires! 
Many games allow you to compete with other players around the world through the 
Internet. Windows includes a variety of card games, puzzle games, and strategy 
games (see Learn about Windows games).

See also
  Parts of a computer 
  Using your mouse 
  Using your keyboard 
  Windows Basics: all topics 