IP Address Explained: What It Is, How to Find It, and How It Works

An IP address (Internet Protocol address) is a numerical identifier used to identify a device or network interface when communicating over an IP network. IP addresses are essential for sending data between devices across local networks and the Internet.

What Is an IP Address?

An IP address is assigned to a device or network interface that communicates using the Internet Protocol. Computers, smartphones, tablets, servers, printers, routers, and other network-connected devices can use IP addresses to communicate with one another.

For example, when you visit a website, your device communicates with the website's server using IP addresses. The server can normally see the public IP address associated with your Internet connection.

Public IP Address vs. Private IP Address

There are two common types of IP addresses you will encounter: public IP addresses and private IP addresses.

Public IP Address

A public IP address is used to identify your connection on the Internet. Your Internet service provider (ISP) typically assigns a public IP address to your router or connection.

Websites and Internet services can generally see the public IP address from which a connection reaches them. However, an IP address alone does not automatically reveal a person's exact physical location or identity.

Private IP Address

A private IP address is used inside a local network, such as your home or office network. Your router may assign private addresses such as 192.168.1.10 or 10.0.0.5 to devices on the network.

IPv4 and IPv6

The two major versions of the Internet Protocol currently in use are IPv4 and IPv6.

IPv4

IPv4 addresses are 32-bit addresses normally written as four decimal numbers separated by dots.

192.168.1.10

IPv4 provides approximately 4.3 billion possible addresses, which is one of the reasons IPv6 was developed.

IPv6

IPv6 uses 128-bit addresses and provides a vastly larger address space. An IPv6 address can look like this:

2001:db8::1

IPv6 also introduces improvements to addressing and network configuration compared with IPv4.

How to Find Your IP Address

The easiest way to find your public IP address is to use a search engine and search for "What is my IP address?". Many websites also provide IP lookup tools.

To find your private IP address, you can use the operating system's network settings or command-line tools.

Windows

Open Command Prompt and run:

ipconfig

Look for the IPv4 Address under the relevant network adapter.

Linux

Open a terminal and run:

ip addr

You can also use:

hostname -I

macOS

You can find your local IP address from System Settings → Network. From Terminal, commands such as ifconfig can also be used.

Can a Website See Your IP Address?

Yes. When you connect directly to a website, the website's server normally receives the source IP address associated with your connection. This is necessary for Internet communication and for the server to send responses back to your connection.

However, an IP address should not be treated as a precise identifier of a person. Multiple people may share one public IP address, and IP geolocation is generally an estimate rather than an exact physical location.

Why Are IP Addresses Important?

• They allow devices and servers to communicate over IP networks.
• They help routers determine where network traffic should be delivered.
• They are used by network administrators for troubleshooting and management.
• They can be used by online services for security, logging, and access control.
• They are an important part of how the Internet routes data between systems.

IP Address and Cybersecurity

IP addresses are commonly encountered during network administration and cybersecurity work. Security professionals may use IP addresses when investigating network traffic, configuring firewalls, analyzing logs, or identifying the source and destination of network connections.

An IP address by itself, however, does not prove who is operating a device. Additional information such as authentication records, application logs, timestamps, and ISP records may be required to associate network activity with a particular account or individual.

Example: Getting an IP Address in C

Older versions of this article used a Windows-specific C program that simply executed ipconfig. A more accurate description is that the program is running the Windows network configuration command, rather than generating an IP address.

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
    system("ipconfig");
    return 0;
}

This program does not generate an IP address. It executes the Windows ipconfig command and displays the network configuration, including available IPv4 and IPv6 addresses.

Important Note About IP Addresses

An IP address is not the same thing as a device's unique hardware identity. For example, a device can receive a different private IP address from its router, and public IP addresses can also change depending on the network and ISP.

In addition, many devices can appear on the Internet through the same public IP address because of technologies such as Network Address Translation (NAT).

Conclusion

An IP address is a fundamental part of Internet and network communication. Understanding the difference between public and private addresses, as well as IPv4 and IPv6, is useful for web development, networking, system administration, and cybersecurity.