What is an IP address and what does it reveal about you?

Every device that talks on the internet needs an address so that data knows where to go, just as a letter needs a postal address. That address is the IP (Internet Protocol) address. You rarely need to think about it, until you set up a server, troubleshoot a network, configure a firewall or wonder what websites know about you. See your current public IP and its approximate location with our what is my IP tool.

IPv4 and IPv6

There are two versions of the Internet Protocol in use.

IPv4

• Written as four numbers from 0 to 255, separated by dots: 203.0.113.42.
• 32 bits long, giving about 4.3 billion possible addresses.
• The global pool of new IPv4 addresses ran out in the 2010s; addresses are now traded and shared heavily using NAT (see below).

IPv6

• Written as eight groups of four hexadecimal digits separated by colons: 2001:0db8:85a3:0000:0000:8a2e:0370:7334, shortened to 2001:db8:85a3::8a2e:370:7334 (leading zeros dropped, one run of zero groups replaced by ::).
• 128 bits long: about 3.4 × 10³⁸ addresses, enough for every device to have its own.
• Adoption is growing steadily. Google’s statistics show roughly half of its users connecting over IPv6 in 2026, with large differences between countries; many mobile networks use IPv6 by default.

Most devices today are dual-stack: they have both an IPv4 and an IPv6 address and use whichever works best.

Public vs private addresses

Your home has many devices but usually just one public IPv4 address. The router handles this with NAT (Network Address Translation): devices inside use private addresses, and the router rewrites traffic so it all appears to come from the public IP.

Private IPv4 ranges (RFC 1918), which are never routed on the public internet:

Other special addresses:

If your router’s WAN address is in 100.64.x.x, you’re behind carrier-grade NAT, which can prevent hosting servers or some games from home.

Dynamic vs static

• Dynamic IP: assigned automatically by your provider via DHCP and can change. This is the norm for home broadband and mobile.
• Static IP: fixed, usually a paid extra for businesses. Useful for hosting servers, VPN gateways, and allowlisting access to company systems.

Inside your home, your router also assigns private addresses dynamically. You can reserve a fixed private IP for a printer or NAS in the router’s DHCP settings.

How IP addresses relate to domain names

People remember names; computers route by number. The DNS translates a domain like example.com into IP addresses: an A record for IPv4 and an AAAA record for IPv6. Use our DNS lookup to see the IPs behind any domain, and read our DNS records guide for the details.

What websites can see from your IP

Every website you visit receives your public IP, because it needs it to send data back. From it, they can usually work out:

• Approximate location: country reliably, region and city often, sometimes wrong by tens of kilometres. Mobile IPs may appear in a different city entirely.
• Internet provider (e.g. BT, Virgin Media, Comcast, Verizon) or the hosting company.
• Connection type: residential, mobile, business, data centre, VPN or Tor exit.

They cannot see from the IP alone:

• Your name, email or street address.
• Your browsing history on other sites.
• Which specific device on your home network you’re using.

However, websites rarely rely on IP alone. Cookies, logins, browser fingerprinting and tracking scripts are far more identifying. In the UK and EU, IP addresses can count as personal data under the GDPR when they can be linked to a person.

VPN basics

A VPN (Virtual Private Network) creates an encrypted tunnel between your device and a VPN server. Websites see the VPN server’s IP instead of yours.

A VPN helps to:

• Hide your IP and approximate location from websites.
• Protect traffic on untrusted public Wi-Fi.
• Prevent your internet provider from seeing which sites you visit (it sees only that you’re connected to a VPN).
• Access your company’s internal network securely.

A VPN does not:

• Make you anonymous: the VPN provider sees your real IP and traffic metadata.
• Block tracking by cookies, logins or fingerprinting.
• Protect you from phishing or malware.

Choose a reputable provider with a clear privacy policy and independent audits.

Troubleshooting with IP addresses

• No internet, IP starts with 169.254: your device didn’t get an address; restart the router or reconnect.
• Two devices with the same IP: an IP conflict, often after setting a static IP manually inside the DHCP range.
• Can’t reach a website but others work: check DNS (does the domain resolve?) and try the IP directly; see our website down guide.
• Find your private IP: ipconfig (Windows), ipconfig getifaddr en0 (macOS) or ip addr (Linux).
• Find your public IP: visit a “what is my IP” page; the router’s admin page also shows its WAN address.

Checklist

• Know whether you need your public or private address.
• Recognise private, localhost, link-local and CGNAT ranges.
• Use a static IP only when you need a stable address.
• Remember that IP location is approximate.
• Use a VPN for privacy on untrusted networks, but don’t treat it as anonymity.