The short version
IPv4 looks like this: 39.45.12.78. IPv6 looks like this: 2001:db8::1. The internet is slowly moving from the first to the second because we have run out of the first.
Why IPv4 ran out
An IPv4 address is 32 bits long, which allows about 4.3 billion unique addresses. That sounded like plenty in the 1980s. Then came smartphones, smart TVs, and a few billion more people online. The last fresh blocks were handed out years ago.
Providers coped with clever workarounds. The biggest is NAT: many customers share one public IPv4 address, with the provider keeping track of whose traffic is whose (carrier-grade NAT). It works, but it breaks things — peer-to-peer connections, some games, self-hosted servers — and adds a layer of bookkeeping to everything.
What IPv6 fixes
IPv6 uses 128-bit addresses: about 340 undecillion of them. Every device can have its own public address again, no sharing tricks needed. As a side effect, many NAT-related headaches disappear.
The tradeoff is transition pain. IPv4 and IPv6 are not directly compatible — a v6-only device cannot talk to a v4-only server without translation. So the whole internet has to run both side by side (“dual stack”) for years while the stragglers catch up.
Which one are you using?
Open our IPv6 test page. It shows which protocol your connection used to reach us. If it says IPv6, your network supports the new protocol. If it says IPv4, that only describes this connection: it often means IPv6 isn’t available to you, but it doesn’t prove your provider lacks it.
Whether you get IPv6 is your provider’s decision, not your device’s — nearly all modern phones, laptops and routers already support it. Some providers let you enable it in the router’s WAN settings; others roll it out on their own schedule.
Should you care?
For everyday browsing: not really. Websites work on both. Where it matters is gaming (stricter NAT types on carrier-grade NAT), running servers from home, and future-proofing. The direction is one-way — IPv6 adoption climbs every year — so the question is when, not if.