MJackson writes: "The American Registry for Internet Numbers (ARIN) has warned that IPv4 (Internet Protocol version 4) addresses, which are assigned to your computer each time you go online (e.g. 126.96.36.199), will run out by 2010. ARIN has now begun issuing letters to ISPs owning blocks of IPv4 addresses, which encourages them to adopt IPv6. The new addresses are claimed to be longer (128bits) and more secure (written in hexadecimal and separated by colons), for example: 2ffe:1800:3525:3:200:f8ff:fe21:67cf . Presently IPv4, used since 1984, provides well over 4 billion addresses, of which only several hundred million remain free and available for new connections."