IPv4 vs IPv6

IPv4 and IPv6 are two versions of internet addressing. IPv4 is older and uses addresses like 203.0.113.10. IPv6 is newer and uses longer addresses like 2001:db8::1.

The main reason IPv6 exists is scale. IPv4 has a limited number of possible addresses. IPv6 provides a vastly larger address space for modern devices and networks.

Why both still exist

The internet cannot switch everything overnight. Many networks run IPv4 and IPv6 together, called dual stack. Some websites support both, while others still depend heavily on IPv4.

Which one do websites see?

It depends on your connection and the website. If both support IPv6, your browser may use IPv6. Otherwise it may use IPv4. A VPN can also change which address type is visible.

Should you worry?

Most people do not need to manage IPv4 or IPv6 manually. But if you use a VPN, check that it handles both properly so your IPv6 address does not leak outside the VPN.

Related: check your IPv4 and IPv6 address.