The Internet routes packets of data from one Internet protocol (IP) address to another. Every Internet-connected device anywhere in the world has its own IP address.

This month's World IPv6 Day served as a test run for a protocol that should dramatically increase how many devices can be connected to the Internet. The new protocol will be crucial if many more objects—including light bulbs, kitchen appliances, and environmental sensors—are to have IP addresses, connect to the Internet, and send and receive data.

What needs replacement is called Internet protocol version 4 (IPv4). This has been the basis for communication between devices since 1981, and it allows for nearly 4.3 billion addresses. The new system allows for around 340 trillion, trillion, trillion addresses—nearly 50 octillion for every person on earth.