In the early years of their development, each computer was a stand-alone device. However, there came a time when people began to think about connecting two computers so that information could be easily moved from one to the other.
A computer network is the hardware and software that allows data to move between computers. A computer network allows computers, and the people using them, to share information, which can be a very powerful means of communication.

Networks are often defined in terms of how big they are.
A LAN is a Local Area Network, which is to say that the network covers a relatively small area, for example, a single building.

A WAN is a Wide Area Network, a type of network that covers a relatively large area. A WAN enables computers to communicate across a country or even around the world. Networks can also be defined in terms of their protocols.
Network Protocol: the rules that a network follows to ensure that computers can communicate. Protocols are very important because they define what one computer must do to communicate with the other computers on a network.
Over the years, different groups of people developed many different types of networks, using various protocols, for connecting computers. If one group used network type "A" for their computers, and another group used network type "B", then the two networks couldn't communicate directly.

Eventually, ways were developed to allow incompatible networks to communicate. A pioneer in this effort was the United States Department of Defense.
They led the invention of one of the most important set of protocols, called TCP/IP, which stands for Transmission Control Protocol/Internet Protocols. This set of rules governs the Internet, which is a "network of networks". Just as a computer network allows many computers to communicate with each other, the Internet allows many different networks to communicate with each other.
The researchers who designed TCP/IP built the first network, named ARPANET, to use these protocols. In 1969, the same year that Armstrong and Aldrin first set foot on the moon, there were only 4 computers on the ARPANET(1). By 1981, that number had grown to only 65 computers, yet by 1993 there were over 1,300,000 computers.(1)

As the Internet began to grow incredibly fast, people thought of many ways to use it. One example you are probably familar with is the "World Wide Web". I'm sure that you have probably used a browser program to access the "World Wide Web".

A browser is the program that runs on your computer that allows you to read a web page that is stored on another computer, which can be literally anywhere in the world. The "Web" was based initially on HyperText Markup Language (HTML), which is a language that was developed in 1991 by Tim Berners-Lee for the specific purpose of displaying information over a network. HTML defines how the information will appear when it is displayed by a browser. HTML and browsers are technologies that made it easy for people to locate and retrieve information from computers. Instead of knowing detailed technical information about a computer, what network protocols it is running, etc, a person only has to click a mouse button. Because HTML is a relatively simple language, it helped make it easy for people to publish information on their computers.

The "Web" is a good example of the principle of information hiding that we talked about last week and is just another example of how people have used their God-given abilities to think through problems and invent new ways to work and play.
Maybe some day you will think of a new way to use computer technology, and we will add the story of your invention to this course.

You can learn more about computers from
“Introduction to Computers – Middle School”,
a 9 week computer-based unit study from StrongTower Software .

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