Europe has almost exhausted its stock of old-style internet addresses.
Strict rationing of these addresses - called IPv4 - has been started by the body that hands them out in Europe.
From now on, companies can only make one more application for IPv4 addresses and, if successful, will only get 1,024 of them.
In addition, any application for more old addresses must demonstrate how an organisation is using the new, replacement, addressing scheme.
"The day has come, finally," said Axel Pawlik, managing director of the Ripe NCC that hands out addresses to European ISPs, firms and other organisations.
Every device that goes online is allocated a unique Internet Protocol (IP) address.
The internet grew up using an addressing scheme called IP Version 4 (IPv4). In the 1970s when the web was being built the 4.3 billion IP addresses allowed by IPv4 were thought to be enough.
However, the rapid growth of the internet and popularity of the web have swiftly exhausted this pool.
The growth of the net is linked to the size of the pool because everything that connects to the net needs an IP address to send and receive data.
Plans are afoot to move to a new scheme, known as IP Version 6 (IPv6), that has an effectively inexhaustible supply of addresses.
On 14 September Ripe NCC got down to its last 16 million IPv4 addresses. While this might sound a lot, said Mr Pawlik, the use of this last substantial block would be so heavily restricted that the supply could be considered to be at an end.
"Applicants will only get about 1,000 addresses," said Mr Pawlik, "and that's it and they only get them once and that's the end of it."
To even get that small number of IPv4 addresses, he said, applicants must already have an allocation of IPv6 addresses and demonstrate how they planned to use them.
Immediately prior to reaching the last big block Ripe was handing out just under four million IPv4 addresses every 10 days.
Anyone planning expansion based around the net should already be committed to using IPv6, said Mr Pawlik.
Other techniques based around technical tricks that share IPv4 addresses among many different devices would prove increasingly unworkable, he said.
"They are complicated, potentially unstable and expensive," he said. "The other route they could go is to v6 as it's in most of the net equipment now."