The "Internet Protocol" (IP) is the technical standard that defines how data is passed across the internet from a source to a destination.
The fourth version of the IP protocol (IPv4) went into service in 1983 when there were only a few dozen devices on the entire Internet.
The addressing system in IPv4 (think of it like a phone number for every device on the internet) was made up of four 8-bit (0-255) numbers, so an IPv4 address looks like something like 192.168.1.1.
The problem is that there are only 4,294,967,296 possible addresses using this scheme, and in practice a lot fewer than that since huge blocks are reserved for various special purposes.
In the mid-90's people started to realize that this internet thing might catch on, and that a day was coming when there just wouldn't be any addresses left. So work began on IPv6, which expands the address format from a 32-bit number to a 128-bit number -- allowing nearly as many potential addresses as there are atoms on the earth.
We are now in this weird transition state where IPv6 is used on much of the internet backbone (including behind the scenes on every LTE cellular network) but many end customer devices are still running IPv4.
The whole system was designed to deal with this to ensure backwards compatibility, but it gets awkward and it can make network engineers lose a lot of sleep.
Overall though - it really isn't anything normal people need to worry about.« Back to Glossary Index