In more precise terms, an IPv6 address is 128 bits long and is arranged in eight groups, each of which is 16 bits. Each group is expressed as four hexadecimal digits and the groups are separated by colons.
Here's an example of a full IPv6 address:
That address can be shortened, however, because the addressing scheme allows the omission of any leading zero, as well as any sequences consisting only of zeroes. Here's the short version:
It has been a concern for some time that the IPv4 addressing scheme was running out of potential addresses. The IPv6 format was created to enable the trillions of new IP addresses required to connect not only an ever-greater number of computing devices but also the rapidly expanding numbers of items with embedded connectivity. In the Internet of Things (IoT) scenario, objects, animals and people are provided with unique identifiers and the ability to automatically transfer data over a network without requiring human-to-human or human-to-computer interaction.
IPv6 expands the available address space sufficiently to enable anything conceivable to have an IP address. The number of potential IPv6 addresses has been calculated as:
According to Computer History Museum docent Dick Guertin, that number allows an IPv6 address for each atom on the surface of the planet-- with enough left over for more than 100 more similar planets.