What is an IP address?
An IP address is the network identifier your traffic uses when it talks to other devices and services. When you open a website, your browser sends requests through routers and providers until the traffic reaches a public destination. The public IP that destination sees is the address your connection presents to the internet at that moment.
- The difference between a public and private IP address.
- Why the same device can have multiple addresses at once.
- Why your IP can change after a reboot, VPN connection, or network handoff.
What it is
IP stands for Internet Protocol. The address is how traffic gets routed back to you after you make a request.
Your phone, laptop, router, VPN, and ISP can all hold different addresses in the path. What matters for websites is the public egress address that leaves your network.
Why it matters
An IP address affects reachability, reputation, geolocation estimates, and how diagnostics like ping, traceroute, and port checks behave.
It is also the fastest clue for figuring out whether you are on IPv4 only, dual-stack, behind a VPN, or moving between networks.
Common mistakes
Many people confuse the IP on a device with the public IP on the internet. A private address like 192.168.1.20 is not what websites see.
Another common mistake is assuming one IP always equals one person. Mobile carriers, VPNs, and NAT gateways can put many users behind the same public address.
How it relates to WhenIP
WhenIP shows the public IPv4 and IPv6 addresses our probes see from your browser session.
That lets you compare families, copy values quickly, and run server-side checks against the address that matters.
Can one device have both IPv4 and IPv6?
Yes. Many networks use both at the same time.
Is my IP address private?
The public IP is visible to sites you visit. A private LAN address usually is not.
Last updated: March 29, 2026