Last week, North America ran out of new addresses based on IPv4, the numbering system that helped bring the internet to where it is today. IPv4 dates back to 1981, and the system only has room for 4.3 billion unique addresses. For years, the American Registry for Internet Numbers (ARIN), the nonprofit group which distributes internet addresses, has been urging enterprises and carriers to adopt the next protocol, IPv6. Introduced in 1999, IPv6 has enough addresses to serve internet users for generations. Users who still need IPv4 addresses can request them from ARIN, but the organization won’t have any to give away unless it receives more from the global Internet Assigned Numbers Authority (IANA), or users who don’t need their addresses return them. You can also buy IPv4 addresses on the transfer market, on which they typically sell for $10-12 USD.