GLOSSARY · EXTERNAL AND INTERNAL IP
Public vs. private IP address
A public IP address is reachable across the internet and is the one websites see. A private IP address is used only inside a local network, such as your home Wi-Fi, and cannot be reached directly from outside. Reserved private ranges include 10.0.0.0 to 10.255.255.255, 172.16.0.0 to 172.31.255.255 and 192.168.0.0 to 192.168.255.255.
Why it matters
Knowing which one you are looking at avoids confusion. The address in your phone's Wi-Fi settings, often starting with 192.168, is private, and tells a website nothing. The public address belongs to your router or your provider's equipment. Private addresses are reused in millions of homes, so two people can have the same one at the same time without conflict.
In practice
If someone asks for your IP address to diagnose a connection, they usually mean the public one. Tools that check the address your connection presents, such as our IP tools, report the public address. A private address can still leak: some browser features can reveal it to websites, which is one reason the WebRTC test exists.
Related terms
- NAT: NAT is a technique where a router rewrites the addresses on outgoing traffic so that many devices with private addresses can share one public IP address.
- IP address: An IP address is a number that identifies a device or network connection on the internet, in the way a street address identifies a building.
- WebRTC: WebRTC is a set of browser features that lets web pages make direct audio, video and data connections between devices, without plug-ins.
- CGNAT: Carrier-grade NAT is NAT performed by an internet provider, not by your own router.