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About six years after the first communications satellite was placed in orbit, the American Department of Defense began developing a new project. It began linking major research universities across the United States. The project began in the early Nineteen-Seventies.
Professors at many American universities do research work for the United States Government. The Department of Defense wanted to link the universities together to help the professors cooperate in their work. Department of Defense officials decided to try to link these universities by computer. The officials believed the computer would make it easier for researchers to send large amounts of information from research center to research center. They believed they could link computers at these universities by telephone.
They were right. It became very easy to pass information from one university to another. University researchers working on the same project could share large amounts of information very quickly. They no longer had to wait several days for the mail to bring a copy of the research reports.
This is how the system works. The computer is linked to a telephone by a device called a modem. The modem changes computer information into electronic messages that are sounds. These messages pass through the telephone equipment to the modem at the other end of the telephone line. This receiving modem changes the sound messages back into information the computer can use. The first modern electronic communication device, the telegraph, sent only one letter of the alphabet at a time. A computer can send thousands of words in a very few seconds.
The link between universities quickly grew to include most research centers and colleges in the United States. These links became a major network. Two or more computers that are linked together form a small network. They may be linked by a wire from one computer to another, or by telephone. A network can grow to almost any size.
For example, let us start with two computers in the same room at a university. They are linked to each other by a wire. In another part of the university, two other computers also are linked using the same method. Then the four are connected with modems and a telephone line used only by the computers. This represents a small local network of four computers.
Now, suppose this local network is linked by its modem through telephone lines to another university that has four computers. Then you have a network of eight computers. The other university can be anywhere, even thousands of kilometers away. These computers now can send any kind of information that can be received by a computer - messages, reports, drawings, pictures, sound recordings. And, the information is exchanged immediately.
Some experts have said it is easier to understand this network of computers if you think of streets in a city. The streets make it possible to travel from one place in the city to another. Major streets called highways connect cities. They make it possible to travel from one city to another.
Computers communicate information in much the same way. Local networks are like the city streets. And communication links between distant local networks are like the major highways. These highways make communication possible between networks in different areas of the world.
In Nineteen-Eighty-One this communication system linked only two-hundred-thirteen computers. Only nine years later, it linked more than three-hundred-fifty-thousand computers. Today experts say there are hundreds of millions of computers connected to networks that provide links with computers around the world. The experts say it is no longer possible to tell how many computers are linked to the information highway. The experts also say the system of computer networks is continuing to grow.
This system of computer networks has had several different names since it began. It is now called the 'Internet.' Almost every major university in the world is part of the Internet. So are smaller colleges and many public and private schools. Magazines, newspapers, libraries, businesses, government agencies, and people in their homes also are part of the Internet.
Computer experts began to greatly expand the Internet system in the last years of the nineteen-eighties. This expansion was called the World Wide Web. It permits computer users to find and exchange written material and pictures much quicker than the older Internet system.
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