The Internet as we know it is now officially too big for its britches.

The organization that assigns IP addresses in North America — the numbers that identify every computer, smartphone and device connected to the Internet — ran out of numbers overnight Wednesday. It's not the end of the world, because there's a newer, more robust system rolling out, but it's a milestone in our shared online history, nonetheless.

IP addresses are the four-number strings like 74.125.224.72 that you'll sometimes see in your browser's address bar, in the guts of your smartphone's system settings, or that you might be asked to type in to your cable modem or WiFi router. That address, 74.125.224.72, is one of many that should take you to Google.com.

It's like the highway system. If you're driving through New York, you might take Interstate 95 or I-190 or I-287. But in plain English, it's all the New York State Thruway.

There are five huge nonprofit regional organizations that hand out those addresses around the world. For the first time, the American Registry for Internet Numbers, in charge of North America, had to turn down a request for a block of addresses Wednesday because it didn't have enough.

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So it activated its "Unmet Request Policy," it said — basically saying sorry, but if you want all of those requested addresses, you'll have to sit on ARIN's waiting list until they somehow become free or buy them on the open market.

Hope your org has all of the IPv4 addresses it needs because the price just went up big time! ARIN is basically out! http://t.co/bhg11XzDij — Matt Peterman (@MattPeterman) June 26, 2015

The problem is there are only those four numbers in addresses, a system called IPv4. It's been in place for more than 30 years, "and even the architects of the Internet could not have predicted the amazing success and universal adoption of the Internet and World Wide Web," said John Curran, president and chief executive of the registry.

"Even optimistically, the total amount of unused or under-used IPv4 address space that could be made available only represents a 'stop gap' measure in the life of the IPv4 Internet," the nonprofit Asia Pacific Network Information Center reported Thursday. "The demand for Internet addresses will only continue to grow."

But the people who run the web have known this was coming for years. In fact, the master organization that doles out addresses for ARIN and the four other regional registries announced more than a year ago that its well was dry.

So work has been under way for years on what's called IPv6 — longer addresses that also include letters. There are only about 4.3 billion possible IPv4 addresses, which engineers assumed would be more than enough in the 1990s. With IPv6, there are about 340 trillion trillion trillion combinations — specifically:

340,282,366,920,938,463,463,374,607,431,768,211,456. (Let's just say 340 gajillion.)

We might be short on IPv4, but not on IPv6! #get6 — ARIN (@TeamARIN) July 2, 2015

Ideally, you shouldn't see any impact from the switchover to IPv6, since both systems are meant to work side by side. But adoption by Internet service providers and large public organizations has been slow. Google, which monitors whether you get to it through IPv4 or IPv6, says only 21 percent of its U.S. traffic comes through IPv6 — and that's the highest rate of any country in the world.

Related: Internet Gets Rewired for the Future With IPv6

"It is time for Internet service providers to move to IPv6 to enable the Internet's continued growth," Curran said. "Businesses should be aware that this transition is already well underway for many service providers in the region and make sure that their public-facing websites are reachable via IPv6."

Otherwise, the Internet will remain frozen where it is today.