Just as there is a limit on the number of telephone numbers, there is also a finite number of Internet (IP) addresses. Every device, such as mobile phones and laptops, and every Web site gets its own unique number. What happens when the current IP addresses run out? That’s where the new Internet addressing system, dubbed IPv6 – those crazy computer engineers at it again – comes in. The system would greatly expand the number of addresses and it is ready to go, but there’s a glitch.