Computers are complex electrical systems that can receive information(input), process it and then output information back to the user. Computers can perform tasks such as calculating, rendering artwork, word processing, page and webpage design, video production, engineering, and communicating. Computers may also be used for recreational purposes, such as playing games, viewing movies or listening to music. Computers are used for many tasks and are a part of many things we do - whether you know it or not. Every time you buy a product at the grocery store, the store's inventory is changed in a giant database that tells them what they need to get more of. When you check out, a computer is used to scan items and calculate your bill. But what if you need money to pay for your groceries? You may have to go to an automated teller machine(ATM) in the store and withdraw some money. Even the ATM is a type of computer. Computers are composed of hardware and software. Hardware is the word for any part of the computer that you can touch. For example - mouse, keyboard, monitor, cpu or printer. Computers require certain pieces of hardware in order to function properly. RAM allows a computer to hold programs or tasks in it's "short-term memory", but it will loose anything in RAM if the computer is restarted. Hard drives inside a computer serve as a storage space or "long-term memory" for all your files and programs. You may also copy files onto removable storage devices such as floppy disks, Zip disks or CD-R's to take to another computer or for back up purposes. Computer 'software' is any program that was written by a software programmer that tells the computer to do something. These programs could perform tasks such as word processing, photo editing, or sending an email. Computer viruses are also a type of software, but these are usually intended to make a computer perform tasks that you would not want them to - like deleting all your files! The computer needs an operating system to manage the many tasks that a computer can do. An example of an operating system would be Microsoft Windows, DOS, Mac OS, UNIX or Linux.
Computers can also be connected together to form a network. Networks are important because they allow us to use computers to directly communicate with others. For example, you may want to send someone an email or instant message, or maybe surf the web to do some research for your paper in American History class. The most common ways a computer can connect to a network is by using a modem and a telephone line or by using a network interface card(NIC) and an ethernet connection. The internet is nothing but a lot of computers all over the world connected together. Networks could also be private, or not accessible from the Internet These kind of networks are called Local Area Networks(LAN) or Wide Area Networks(WAN). One way to keep your LAN private from the Internet is to set up a firewall. Firewalls are computers, software or other devices that are designed to let your LAN computers have access to view the Internet, but not allow people outside your LAN to get to your computers. You could think of a firewall as a sort of "body guard" that protects your local network from intruders. Proxy servers are used to filter out content on the Internet and to speed up Internet usage. To find out more about how Internet connections work, check out How Stuff Works' section on Internet connections. Here is a chart comparing some of the different types of internet connections that are available:
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