IPv6 was designed to solve one core problem: IPv4 simply doesn't have enough addresses for a world with billions of connected devices. Understanding its basic design explains why it looks so different from the familiar dotted-decimal format.
The address space, in perspective
IPv4 offers about 4.3 billion addresses. IPv6 offers roughly 340 undecillion (that's 3.4 followed by 38 zeros) — a number large enough that address scarcity, the driving problem behind NAT and the private/public address split, essentially stops being a concern.
Hexadecimal notation
Where IPv4 uses four decimal numbers, IPv6 addresses are written as eight groups of four hexadecimal digits, separated by colons — like 2001:0db8:0000:0000:0000:0000:0000:0001. Consecutive groups of zeros can be abbreviated with a double colon, shortening that same address to 2001:db8::1. See How to Read an IPv6 Address for the full notation rules.
End-to-end addressing
Because there's no scarcity to solve, IPv6 was designed around every device potentially having its own globally routable address, rather than relying on NAT to share a small number of public addresses across many devices — a meaningful architectural difference from how most IPv4 networks operate today.
Coexistence with IPv4
IPv6 doesn't replace IPv4 overnight — most connections today run both protocols simultaneously in what's called dual-stack configuration. See IPv4 vs IPv6 for what this coexistence actually means in practice, including why it's the source of a specific, common category of VPN leak.
FAQ
Do I need to do anything to use IPv6?
Generally no — if your ISP and router support it, your devices typically use it automatically alongside IPv4 without any manual configuration.