IPv4 vs IPv6: What Is the Difference?

IPv4 has been the workhorse of the internet for decades. With only about 4.3 billion possible addresses, it ran out long ago. IPv6, with 340 undecillion addresses, was designed to remove that ceiling and modernize how the internet routes traffic.

Address format

IPv4 uses four numbers separated by dots, like 198.51.100.5. IPv6 uses eight groups of hexadecimal characters separated by colons, like 2001:0db8:85a3::8a2e:0370:7334. Leading zeros can be compressed.

Do I need to choose one?

For end users, no. Modern operating systems and browsers use whichever protocol is available, often both. If a site supports IPv6 and your connection does too, you may be reaching it over IPv6 without noticing.

Why developers care

Server software, firewalls, logging, and analytics must understand both. Geolocation databases for IPv6 are improving but still less precise than IPv4 in many regions.