What is IPv4 (Internet Protocol Version 4)?
IPv4 is the most widely deployed Internet protocol used to connect devices to the Internet. IPv4 uses a 32-bit address scheme allowing for a total of 2^32 addresses (just over 4 billion addresses).
With the growth of the Internet it is expected that the number of unused IPv4 addresses will eventually run out because every device -- including computers, smartphones and game consoles -- that connects to the Internet requires an address.
What is IPv6 (Internet Protocol Version 6)?
The Internet Protocol version 6 (IPv6) was designed as an evolutionary upgrade to the Internet Protocol and will, in fact, coexist with the older IPv4 for some time. IPv6 was designed to allow the Internet to grow steadily, both in terms of the number of hosts connected and the total amount of data traffic transmitted.
What is the difference?
An IPv4 address is binary numbers but can be stored as text for human readers. For example, a 32-bit numeric address (IPv4) is written in decimal as four numbers separated by periods. Each number can be zero to 255. For example, 126.96.36.199 could be an IP address.
IPv6 addresses are 128-bit IP address written in hexadecimal and separated by colons. An example IPv6 address could be written like this: 3ffe:1900:4545:3:200:f8ff:fe21:67cf.
What are the benefits of IPv6?
While increasing the pool of addresses is one of the most often-talked about benefit of IPv6, there are other important technological changes in IPv6 that will improve the IP protocol:
No more NAT (Network Address Translation)
No more private address collisions
Better multicast routing
Simpler header format
Simplified, more efficient routing
True quality of service (QoS), also called "flow labeling"
Built-in authentication and privacy support
Flexible options and extensions
Easier administration (say good-bye to DHCP)