Some of the world's biggest Internet companies will switch from Internet protocol version 4 to Internet protocol version 6, or IPv6, next week in an effort to make the Web accessible to more devices. IPv4 standards had limitations on the number of IP addresses it could support. Beginning June 6, companies like AT&T, Bing, Cisco, D-Link, Facebook, Google, and Yahoo will participate in the transition and move to the next-generation Internet protocol, IPv6.