An IP address (Internet Protocol address) is a unique address that each computer uses to communicate using the internet. The IP address acts as a locator for one IP device to find another and interact with it.
Most of us who are used to computers have at some point had to setup the IP and DNS settings to connect to the internet. Vista has a new option in the connection properties – TCP/ IP v6. This was never seen in Windows XP.
So what is TCP / IP 6 ? The current version of TCP / IP in use is v4 which is a 32 bit number (example 188.8.131.52). A 32 bit number can represent upto 4 billion unique IP addresses. Now more and more people using computers, its just a matter of time before all these unique IP’s are in use.
TCP / IP v6 is a 128 bit number, made up of hexadecimal digits separated by colons. An example would be something like 85ah:16ag:3wfg:324m:63rh:64gd:3sgh:987f
For now there is nothing to worry about, but in due time we will have to switch to the new version. Its good to know that Vista is prepared to make the switch.
You can read more about IP address at Wikipedia