Part of what makes the Internet so robust is the numerous ways data can travel across the system. There are physical lines that connect computers together -- these are usually made out of copper wire or fiber-optic cables. Radio towers, cell phone towers, 4G towers and satellites also can transmit data across the Internet. Then there are the thousands of computers that act as clients, servers or both. These computers are the connection points that allow information to pass from one computer to another, even if the two computers are on opposite sides of the Earth.
To really understand how data travels along the Internet, it's helpful to look at a specific transmission. Let's say you're visiting your sister and the two of you want to go out for sushi. She's new to town and doesn't know a good sushi place but overheard her co-workers talking about a place last week and thinks she'll recognize the name. You search for sushi bars from her laptop, which is wireless, while sipping tea on her back patio. The WiFi connection goes to a router in her living room, which is hooked up to her digital subscriber line, or DSL, that comes in through her phone jack. You notice that right away, because at home, you get your Internet through cable. The request you sent with her browser goes through a dedicated line in her phone company's cable, to her Internet provider's server, and seeks the IP address for Google.
You don't really know where the data goes at Google, but estimates are that the search engine uses at least 900,000 servers [source: Fehrenbacher]. The company doesn't publicize how its servers work or are connected, but you can bet there is quite a tangle of high-speed wiring and a redundant server. All you know is you get instantaneous results. Your sister spots the name of the sushi bar, you peruse a review, and the two of you head out for a California roll.
Remember -- your sister has not lived here long, and she walks to work. You get lost trying to find the downtown sushi bar, but that's OK, because you both have your smartphones on hand. With 4G capabilities, you head back online from the car (while she drives, of course) and look up the restaurant directions again, along with a wider map view. A few right and left turns later, you're there.
When you get home, you upload the photos you took on your trip to Facebook through your wired desktop computer, cable connection and onto Facebook's server. Your sister and your friends can check out the great time you had from any number of transmission methods.
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