What Is an IP Address? How It Works and How to Check Yours

What Is an IP Address?

Every device connected to the internet is assigned a unique identifier known as an IP address (Internet Protocol Address). Just as a postal address is needed to deliver mail, an IP address is essential for routing data accurately across the internet.

When you browse a website, your browser sends a request to a server, and the server returns its response to your device. IP addresses are what make this entire exchange possible — they are the foundational technology underpinning all internet communication.

IPv4 and IPv6 — Two Generations

Two generations of IP addresses coexist on today's internet.

IPv4: Features and Limitations

Defined in 1981, IPv4 uses a format of four numbers separated by dots, such as "192.168.1.1." It supports approximately 4.3 billion addresses — a number that seemed more than sufficient at the time but has since been exhausted due to the explosive growth of the internet.

The Solution IPv6 Brings

Designed as the successor to IPv4, IPv6 uses hexadecimal notation separated by colons, such as "2001:0db8:85a3::8a2e:0370:7334." Its address space encompasses roughly 340 undecillion addresses — a virtually limitless supply. Beyond solving the address exhaustion problem, IPv6 also delivers significant security improvements, including native support for encrypted communication via IPsec. The global transition from IPv4 to IPv6 is well underway and will only accelerate.

Global IP vs. Private IP

IP addresses fall into two broad categories based on their role.

Global IP Address

A globally unique address that identifies your device on the internet. Assigned by your ISP (Internet Service Provider), it enables communication from anywhere in the world. The address displayed on the Kakunin-san homepage is your global IP address.

Private IP Address

An address used only within a local network, such as a home or office. Routers use NAT (Network Address Translation) to bridge private and global IP addresses. Common private IP ranges include:

  • 10.0.0.0 – 10.255.255.255 (Class A)
  • 172.16.0.0 – 172.31.255.255 (Class B)
  • 192.168.0.0 – 192.168.255.255 (Class C)

What Information Can Be Derived from an IP Address?

An IP address can be used to infer the following types of information:

  • Approximate geographic location (country, region, and city level)
  • Your ISP
  • AS number (Autonomous System Number)
  • Connection type (broadband, mobile, etc.)

It is important to note, however, that an IP address alone cannot reveal your exact home address or personal identity. GeoIP database estimates typically carry an error margin of several to tens of kilometers.

How to Check Your IP Address

There are several ways to check your IP address, but the easiest is to use a web tool like Kakunin-san.

  • Visit the Kakunin-san homepage (also displays GeoIP data and ISP information)
  • Run ipconfig (Windows) or ifconfig (macOS/Linux) in a command prompt or terminal
  • Check the WAN IP address in your router's admin panel

IP Addresses and Privacy

When combined with browsing history, an IP address can serve as a clue for tracking user behavior patterns. The following measures can help mitigate this risk:

  • Use a VPN to conceal your IP address
  • Use the Tor Browser for enhanced anonymity
  • Route your traffic through a proxy server

For more details on these technologies, see our articles on VPNs and the Tor Browser.