The world is about to run out of the Internet addresses that allow computers to identify each other and communicate, the man who co-developed the system has told The Times.
Vint Cerf, often called the "father of the Internet" and one of the world's leading computer-networking scientists, said that businesses and consumers needed to act now to switch to the next generation of Internet addresses.
Unless preparations were made now, he said, some computers might not be able to go online and the connectivity of the Internet might be damaged.
Cerf said that Internet service providers in particular needed to prepare, and that time was running out for a smooth transition.
Every computer and online device is assigned a unique Internet Protocol address — Windows users can look up theirs by opening a command-prompt window and typing "ipconfig" — but the pool of unallocated numbers is about to dry up.
"This is like the Internet running out of telephone numbers and with no new numbers, you can't have more subscribers," he said.