1. I'm Barbara Klein. And I'm Steve Ember with EXPLORATIONS in VOA Special English. Today we present the second part of our series about communications. We tell how computers are linking people around the world.
2. Last week, we told about the early history of the communication of information. We described how the telegraph was the first important device that could move information quickly from one place to another. And we discussed early radio and television broadcasts and the beginning of satellite communications.
3. In the early nineteen seventies, the American Department of Defense began developing a new project. It began linking major research universities across the United States.
4. 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.
5. 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.
6. They were right. It became very easy to send 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.
7. 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.
8. 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 within seconds.
9. 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.
10. For example, let us start with two computers in the same room at a university. A wire links them to each other. 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 computers. This represents a small local network of four computers.
11. 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.
12. These computers can now send any kind of information that can be received by a computer - messages, reports, drawings, pictures, sound recordings. And, the information is exchanged immediately.
13. Since it began, this system of computer networks has had several different names. It is now called the Internet. In nineteen eighty-one, this communication system linked two hundred thirteen computers. Only nine years later, it linked more than three hundred fifty thousand computers. Today, experts say more than one billion people around the world are linked by computers to the Internet. And, they say, this number will continue to grow.
14. 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.
