IPv6 is a 128-bit routed protocol. Because the IPv4 protocol is running out of address space, IPv6 was developed. The huge size of IPv6 allows for further growth of the Internet, whereas staying with IPv4 only would limit the amount of devices able to connect to the Internet.
IPv6 is represented using eight groups of four hexadecimal digits separated by colons.
Most operating systems will allow a dual stack. That is, they will have both IPv4 and IPv6 addresses assigned to them at the same time, and will use which ever of those addresses is most convenient.