IPv4 stands for Internet Protocol version 4. It is the originalstandard set up for handling IP addresses when the Internet was initialdeveloped by DARPA (Defense Advanced Research Projects Agency) in the early1970s.
IPv4 uses a 32 bit address field which provides for 4,294,967,296 uniqueInternet addresses. This is the number of computers/devices that can beconnected to and use the Internet. In the early 1970's the population of theearth was less than 4 billion people, personal computers did not exist, and atmost there were hundreds, perhaps thousands of mainframe and mini computersthat had been assigned Internet addresses. So the 4 billion plus address spacewas deemed to be more than enough to last beyond any foreseeable requirements.
IPv4 addresses are all but consumed
By 1992, the rapid explosion of the Internet fueled by the vast number ofpersonal computers attaching to it, made it clear that the IPv4 address spacewas already consumed to the point that a replacement had to be found.
IPv6 was developed in response to this situation. IPv6 allocates 128 bits tomap the Internet address space. The number of bits were not just doubled, butinstead quadrupled from IPv4's 32 bits to insure that this address space wouldnot run out any time soon!
IPv6 addresses will probably neverrun out
128 address bits provide IPv6 with 340,282,366,920,938,463,463,374, 607,431,768,211,456unique addresses. It may seem like overkill to have this many addressesavailable, However, many visionary individuals believe that eventually everywired and wireless computer, cell phone, PDA, household appliance, securitycamera, devices that haven't yet been invented, will each have their own uniqueInternet address.
Besides the huge number of IP addresses, IPv6 provides for better handling ofvoice than IPv4 which was not initially set up to handle it. This means thatphone conversations over the Internet will be smooth and clear instead ofchoppy and broken up like they often are now.
The time is almost upon us when any device with an Internet address and aconnection to the Internet can be monitored and controlled from anywhere in theworld. While you're away on vacation you could turn on lights, change yourthermostat, check security cameras around your home, etc. The possibilities areonly limited by our imagination!