Online addresses are becoming increasingly scarce. This means that the value of unused addresses is likely to rise. Because of the millions of new computers, cell phones, and other devices going online, the supply of Internet Protocol (IP) addresses is dwindling. There are only 4 billion number combinations possible, and an Internet registry group has estimated that the 1 billion unallocated addresses remaining will run out by 2010. The familiar addresses, like businessweek.com, merely represent human-friendly names that have numerical equivalents. The equivalents allow one device to find another one online. The migration to an upgraded version of the Internet that would provide access to billions of devices is moving slowly and will not stop the coming shortage of addresses. Some industry analysts say this could be a significant opportunity for the holders of so-called legacy addresses. Legacy address holders obtained hundreds of millions of addresses at the beginning of the Internet. These legacy holders range from individuals to some large corporations that hold many millions of addresses each. Since they obtained control of IP addresses before Internet governing authorities were developed, they are not bound by the same contractual requirements as firms and individuals who lease IP addresses from Internet registries. It is unclear whether legacy holders can sell the addresses legally, however.