IPv4 allowed for four billion ip addresses....

What ya gonna do with all 340,282,366,920,938,463,463,374,607,431,768,211,456 of the ip addresses IPv6 provides? That's three hundred and forty undecillion, two hundred and eighty-two decillion, three hundred and sixty-six nonillion, nine hundred and twenty octillion, nine hundred and thirty-eight septillion, four hundred and sixty-three sextillion, four hundred and sixty-three quintillion, three hundred and seventy-four quadrillion, six hundred and seven trillion, four hundred and thirty-one billion, seven hundred and sixty-eight million, two hundred and eleven thousand, four hundred and fifty-six.

Here’s how Wikipedia expresses it:

"The very large IPv6 address space supports a total of 2128 (about 3.4×1038) addresses - or approximately 5×1028 (roughly 295) addresses for each of the roughly 6.5 billion (6.5×109) people alive today. In a different perspective, this is 252 addresses for every observable star in the known universe."

Steve Leibson takes a shot at putting it in real world terms.

"So we could assign an IPV6 address to EVERY ATOM ON THE SURFACE OF THE EARTH, and still have enough addresses left to do another 100+ earths. It isn’t remotely likely that we’ll run out of IPV6 addresses at any time in the future."