The IPv6 launch has expanded the number of Internet addresses to 340 undecillion.

NEW YORK (CNNMoney) -- One of the crucial mechanisms powering the Internet got a giant, years-in-the-making overhaul on Wednesday.

When we say "giant," we're not kidding. Silly-sounding huge number alert: The Internet's address book grew from "just" 4.3 billion unique addresses to 340 undecillion (that's 340 trillion trillion trillion). That's a growth factor of 79 octillion (billion billion billion).









If it all goes right, you won't notice a thing. And that's the point.

The Internet is running out of addresses, and if nothing were done, you certainly would notice. New devices simply wouldn't be able to connect.

To prevent that from happening, the Internet Society, a global standards-setting organization with headquarters in Geneva, Switzerland; and Reston, Va., has been working for years to launch a new Internet Protocol (IP) standard called IPv6.

IP is a global communications standard used for linking connected devices together. Every networked device -- your PC, smartphone, laptop, tablet and other gizmos -- needs a unique IP address.

With IPv6, there are now enough IP combinations for everyone in the world to have a billion billion IP addresses for every second of their life.

That sounds unimaginably vast, but it's necessary, because the number of connected devices is exploding. By 2016, Cisco (CSCO, Fortune 500) predicts there will be three networked devices per person on earth. We're not just talking about your smartphone and tablet; your washing machine, wristwatch and car will be connected too. Each of those connected things needs an IP address.

Then there's all the items that won't necessarily connect to the Internet themselves, but will be communicating with other wired gadgets. Developers are putting chips into eyeglasses, clothes and pill bottles. Each one of those items needs an IP address as well.

The current IP standard, IPv4, was structured like this: xxx.xxx.xxx.xxx, with each "xxx" able to go from 0 to 255. IPv6 expands that so each "x" can be a 0 through 9 or "a" through "f," and it's structured like this: xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx. (Yes, there was an IPv5, but it was a streaming multimedia standard developed in the late 1970s that never really caught on).

The changeover is akin to when the U.S. telephone system handled soaring growth by increasing the digits in each telephone number -- except for one crucial difference. While the entire telephone system was upgraded in the 1990s, the Internet will be upgraded gradually.

IPv4 will continue to exist alongside IPv6 for quite some time, just as digital and analog TV were broadcast side-by-side for years.

Though most of the major Internet players will be IPv6 compliant going forward, many routers, devices and operating systems won't be. For instance, Microsoft (MSFT, Fortune 500) Windows XP, the world's most-used PC operating system, is not IPv6-compliant.

Just 1% of end users are expected to now be reaching websites using the IPv6 standard. The Internet Society expects that to gradually grow as users update their software and hardware.

Most of the major websites and networks are already participating. More than 2,000 websites, including Google (GOOG, Fortune 500), Facebook (FB), Bing, Yahoo (YHOO, Fortune 500), AOL (AOL) and Netflix (NFLX), as well as a number of network operators such as AT&T (T, Fortune 500), Verizon (VZ, Fortune 500), Comcast (CMCSA) and Time Warner Cable (TWC, Fortune 500), have begun enabling IPv6.

But they'll all need to continue to support IPv4 until the entire world upgrades. That will take years.

There have been some grumblings about cyberattackers getting ready to pounce on Wednesday, taking advantage of potential holes in a new technology. But a year ago, on June 8, 2011, all those participating networks and sites turned on IPv6 for a day-long test run without a hitch.

They reverted to IPv4 the next day. This time, the change is permanent. It'll be a slow transition, but it's a crucial one that will support the Internet's current rate of expansion far into the future.