How Computers Open Lines of Communication
On the Internet, you can connect to the Daily Telegraph in London or the Louvre in Paris or the White House in Washington or Cousin Sid in Moose Jaw.
Leonard Kleinrock, the UCLA professor of computer science who helped start it all in 1969, explains how that is possible:
The backbone of the Internet is really the familiar phone companies. The same networks that carry your voice long distances--AT&T;, Sprint, MCI and others--also carry the chatter from your computer.
First, you subscribe to a computer service that offers Internet access. If you have a typical personal computer, it dials the local phone number for your computer service and tells it you want to go to, say, https://www.nypl.org, the New York Public Library’s Internet address.
The computer service consults its router, a computer that acts as a combination information operator and long-distance operator. It looks up the address you specified, finds the corresponding Internet phone number (which can be as many as 12 digits) and sends your message via high-speed phone lines to, say, AT&T;’s nearby router.
AT&T; passes the message along to its next router, and on and on--often through competitors’ networks as well. It reaches the library’s computer in New York within a fraction of a second--if Internet traffic is light.
The library computer now has your Internet address and sends back its “home page,” which appears on your computer screen as a colorful, illustrated poster showing the library’s resources and features.
By selecting one of the features--”catalogs,” for instance--your computer sends an entirely new message back to the library, and the list of catalogs is sent back to you.
Heavy Internet traffic can slow communications, but the Internet is as efficient as it is because it does not tie up lines while it waits. Computers send a message as a spurt of information, then wait for a reply. During the wait, other computers can use the line.
More information on the Internet, including its uses and history, is available at the Public Broadcasting Service’s Internet site: https://www.pbs.org/internet
