How big is the Net?

How big is the Internet? It seems like a simple question until you try to answer it.

One of the problems is that the Internet is a distributed system and not a centralized one. Think of mail delivery in your neighborhood. This is a centralized system. Each piece of mail goes to or comes from the post office.

If mail delivery were a distributed system, then any house could send or deliver mail to any other house directly. That is how the Internet works, but instead of houses there are computers.

This structure has engendered a persistent Internet factoid: That the military commissioned the Internet and specified a distributed system so that a nuclear attack could not knock out the network. Charles Herzfeld, a director of the defense department agency that built the Net, said, "The ARPANET (precursor of the Internet) was not started to create a Command and Control System that would survive a nuclear attack, as many now claim." The Internet was built as a distributed system so that a failure of any one part would not bring down the whole network. Things were not as reliable back when the Net was built.

So if we asked how big the postal system was in our neighborhood, we could count the number of pieces of mail coming through the post office. But there is no post office on the Internet.

The other problem is how you ask the question. Do you mean how any computers are on the Internet? How many people use it? How much data does it contain? How many Web sites there are?

Even those more specific questions are hard to answer, but there have been attempts.

According to internetworldstats.com, about 1.8 billion people were using the Internet at the end of 2009. That is a little over a quarter of the world's population. Usage has grown almost 400 percent since the end of 2000. Asia has the most users because of its population, but only one out of five people in Asia use the Net. In North America, three out of four do.

To many people, the Internet is the World Wide Web.

Microsoft's Bing search engine team estimates the amount of Web pages at over one trillion. PCMemoirs.com says that if you read each page for one minute, it would take you more than 31,000 years to read them all. And to confirm this number, Google says it has already indexed more than one trillion discrete Web addresses.

How much information does the Internet contain?

The only estimate TechMan could find was by Eric Schmidt, CEO of Google, who said the amount of data on the Net was 5 billion gigabytes. And that was about five years ago.

Let's look at it in terms of hardware. One estimate is that there are 75 million servers worldwide, but some say the number could be five times that. But of course devices other than servers connect to the Internet -- cell phones for example. Each device that connects must have an IP address, just as in our post office example each house must have an address.

These addresses consist of a set of numbers, four groups of up to three digits separated by periods. Using all the possible combinations of these 12 numbers provides about 4 billion possible addresses in IPv4, the current system.

But with an increasing number of devices being connected to the Internet (in the future your kitchen appliances will be Internet-aware) IPv4 will run out of addresses in a few years.

To solve that, a new standard is being worked out that uses a longer string of numbers for each address. This standard, called IPv6, expands the number of addresses available to 340 trillion trillion trillion, a number so large as to be virtually meaningless. Wikipedia says it equals a number of IP addresses as large as the number of atoms in a metric ton of carbon for each of the 6.8 billion people alive today.

Any way you look at it, the Internet is mammoth, and it is growing by leaps and bounds, or clicks and bytes.