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How does the Internet work?

A Matter of Protocols
The Internet is a global entity -- you could call it the largest machine on Earth.
The Internet is a global entity -- you could call it the largest machine on Earth.
Jeffrey Hamilton/Lifesize/Thinkstock

You've probably heard of several protocols on the Internet. For example, hypertext transfer protocol is what we use to view Web sites through a browser -- that's what the http at the front of any Web address stands for. If you've ever used an FTP server, you relied on the file transfer protocol. Protocols like these and dozens more create the framework within which all devices must operate to be part of the Internet.

Two of the most important protocols are the transmission control protocol (TCP) and the Internet protocol (IP). We often group the two together -- in most discussions about Internet protocols you'll see them listed as TCP/IP.

What do these protocols do? At their most basic level, these protocols establish the rules for how information passes through the Internet. Without these rules, you would need direct connections to other computers to access the information they hold. You'd also need both your computer and the target computer to understand a common language.

You've probably heard of IP addresses. These addresses follow the Internet protocol. Each device connected to the Internet has an IP address. This is how one machine can find another through the massive network.

The version of IP most of us use today is IPv4, which is based on a 32-bit address system. There's one big problem with this system: We're running out of addresses. That's why the Internet Engineering Task Force (IETF) decided back in 1991 that it was necessary to develop a new version of IP to create enough addresses to meet demand. The result was IPv6, a 128-bit address system. That's enough addresses to accommodate the rising demand for Internet access for the foreseeable future [source: Opus One].

When you want to send a message or retrieve information from another computer, the TCP/IP protocols are what make the transmission possible. Your request goes out over the network, hitting domain name servers (DNS) along the way to find the target server. The DNS points the request in the right direction. Once the target server receives the request, it can send a response back to your computer. The data might travel a completely different path to get back to you. This flexible approach to data transfer is part of what makes the Internet such a powerful tool.

Let's take a closer look at how information travels across the Internet.