IPv4 vs IPv6: What's the Difference?
Every device online needs an address, and the internet currently runs on two different addressing systems at once. Here's what separates them.
What is IPv4?
IPv4 is the original addressing system the internet was built on. It writes addresses as four numbers separated by dots, like 192.168.1.1, where each number ranges from 0 to 255. That format allows for roughly 4.3 billion unique addresses.
When the system was designed in the early 1980s, 4.3 billion seemed like more than the world would ever need. Between the growth of the internet, mobile devices, and connected smart devices, that pool has effectively run out.
What is IPv6?
IPv6 is the newer system designed to solve that shortage. It uses a much longer format — eight groups of letters and numbers separated by colons, like 2001:0db8:85a3:0000:0000:8a2e:0370:7334. This gives IPv6 an address space large enough that it's effectively impossible to exhaust.
Side-by-side comparison
| | IPv4 | IPv6 |
|---|---|---|
| Format | 32-bit, e.g. 192.168.1.1 | 128-bit, e.g. 2001:0db8::1 |
| Total addresses | ~4.3 billion | Effectively unlimited |
| Introduced | 1983 | 1998 (adoption ongoing) |
| Configuration | Often manual or via DHCP | Built-in auto-configuration |
Why do both still exist?
Switching the entire internet over to IPv6 overnight isn't possible — it requires every router, server, and internet provider to support it. So the two systems run side by side during a transition that's been ongoing for over two decades. Most home networks today are assigned both an IPv4 and an IPv6 address simultaneously.