What is an IP address?
An IP address (Internet Protocol address) is a numerical label assigned to every device connected to a network. It serves two functions: identifying the device and providing its location on the network for routing purposes.
IPv4
The most common format: four numbers from 0-255 separated by dots.
Example: 192.168.1.1 or 8.8.8.8
IPv4 supports about 4.3 billion unique addresses — a number that seemed enormous in 1981 but has been essentially exhausted as the internet grew.
IPv6
The modern format: eight groups of four hexadecimal digits separated by colons.
Example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
IPv6 supports 340 undecillion addresses (3.4 × 10³⁸) — enough for every atom on Earth to have its own address.
What information an IP address reveals
When you look up an IP address, you typically find:
Geographic information (approximate):
- Country (highly accurate, ~99%)
- Region/state (fairly accurate, ~80%)
- City (moderately accurate, ~60-80%)
- Postal code (less accurate, ~50%)
- Latitude/Longitude (city-level precision, not building-level)
Network information:
- ISP (Internet Service Provider): Verizon, Comcast, AT&T, etc.
- Organization: The company or entity that owns the IP block
- AS Number: The Autonomous System number identifying the network
- Hostname: The domain name associated with the IP (if any)
- Connection type: broadband, mobile, data center, satellite
Security indicators:
- Whether the IP is a known VPN exit node
- Whether it's a proxy server
- Whether it's a Tor exit node
- Whether it's associated with data center hosting
How IP geolocation works
IP addresses are allocated in blocks to organizations (ISPs, companies, universities) by regional internet registries (ARIN, RIPE, APNIC, LACNIC, AFRINIC). These registrations include the organization's location.
Geolocation databases map IP ranges to locations through:
- Registry data: Official registration records show where the IP block was assigned
- BGP routing data: How traffic routes to that IP reveals geographic path
- User-contributed data: When users self-report their location, correlated with their IP
Important limitation: IP geolocation shows where the internet infrastructure is, not necessarily where the user is. A VPN user in Vietnam connecting through a server in Singapore shows a Singapore IP. A mobile user may show their carrier's data center city, not their actual city.
Public vs private IP addresses
Public IP
Your publicly routable address on the internet — the address websites see when you visit them. Assigned by your ISP. This is what IP lookup tools show.
Private IP
Used within local networks (home, office). Not routable on the internet:
- 10.0.0.0–10.255.255.255
- 172.16.0.0–172.31.255.255
- 192.168.0.0–192.168.255.255
Your laptop may have IP 192.168.1.5 on your home network, but websites see your router's public IP (e.g., 203.0.113.45).
Common uses for IP lookup
Security and fraud detection: Verifying whether a login attempt comes from an unusual location, detecting VPN/proxy usage, identifying suspicious traffic patterns.
Content localization: Websites use IP geolocation to serve content in the correct language, currency, or region-specific version.
Network troubleshooting: Tracing where traffic is originating from or being routed through.
Compliance: Geo-restrictions for licensed content (streaming services) or regulatory compliance.
Research: Understanding where website traffic originates.
Privacy implications
Your IP address is visible to every website you visit — it's how websites know where to send the response. While an IP alone doesn't identify you personally (ISPs retain the records linking IPs to accounts), it does reveal:
- Approximate location (city level)
- Your ISP
- Whether you're using a VPN or proxy
Using a VPN replaces your real IP with the VPN server's IP, changing what websites see about your location and provider.
How to look up any IP address free
- Go to IP Address Lookup
- Your own IP is automatically detected on load
- Enter any IPv4 or IPv6 address to look it up
- See location, ISP, ASN, and security details