An IPv4 address is a set of four numbers separated by dots that identifies your device on the internet

An IPv4 address looks like this: 192.168.1.1. Each of the four numbers can range from 0 to 255, which gives the system about 4.3 billion possible addresses. Your computer, phone, printer, or any device that connects to the internet needs one to send and receive data. Think of it like a mailing address — the internet uses it to know where to send information and where it came from.

IPv4 stands for Internet Protocol version 4. It has been the standard way devices talk to each other online since the 1980s. Every time you load a website, send an email, or stream video, your device's IPv4 address is part of that conversation. Without it, the receiving computer would not know where to send the response.

You have probably seen your own IPv4 address without realizing it. If you open your network settings or router page, you will find a number that looks like 192.168.0.5 or 10.0.0.1. That is your device's address on your local network. Your internet service provider also assigns you a different IPv4 address that the rest of the internet sees when you browse.

Key Takeaways

  • An IPv4 address is four numbers from 0 to 255 separated by dots, and it identifies your device on a network or the internet.
  • Your device has two IPv4 addresses: a local one for your home network and a public one that your internet service provider assigns for the wider internet.
  • The four numbers are divided into two parts — the network portion tells routers which network your device is on, and the host portion identifies your specific device.
  • IPv4 addresses are running out because there are only about 4.3 billion possible combinations, which is why IPv6 was created as a replacement with far more addresses available.

Public and private IPv4 addresses serve different purposes

Your public IPv4 address is assigned by your internet service provider and is visible to every website and service you visit online. When you check "what is my IP" on a search engine, you see this number. Websites use it to know where to send web pages back to you. This address changes periodically — sometimes daily, sometimes monthly, depending on your provider's setup.

Your private IPv4 address is used only within your home or office network. It never leaves your local network and is not visible to the outside internet. Your router assigns this address to your devices automatically. Common private addresses start with 192.168, 10.0, or 172.16. These ranges are reserved specifically for private use, so no device on the public internet will ever have one.

Your router acts as a translator between these two worlds. When you request a webpage, your device sends the request with its private address. The router receives it, replaces the private address with your public address, and sends it out to the internet. When the webpage comes back, the router sees it is meant for your public address, translates it back to your private address, and sends it to your device.

How the four numbers in an IPv4 address are organized

Each IPv4 address is split into two logical parts: the network portion and the host portion. The network portion tells routers which network a device belongs to. The host portion identifies the specific device on that network. A subnet mask determines where one part ends and the other begins.

In a home network, the subnet mask is usually 255.255.255.0. This means the first three numbers identify the network, and the last number identifies the device. So in the address 192.168.1.5, the network is 192.168.1, and 5 is your specific device. All devices on your home network will have addresses like 192.168.1.1, 192.168.1.2, 192.168.1.3, and so on.

Larger networks use different subnet masks to organize more devices. A business might use 255.255.0.0, which means the first two numbers identify the network and the last two identify devices. This allows for up to 65,000 devices on a single network instead of just 254. The subnet mask is not something you usually need to change — your router or network administrator sets it up.

Why IPv4 addresses are running out and what comes next

With only about 4.3 billion possible IPv4 addresses and over 8 billion people on Earth, plus billions of devices that are not phones or computers, the supply is stretched thin. Many addresses are wasted or held by organizations that do not use them all. Internet service providers now carefully manage the addresses they have, and some reuse addresses by taking them away from inactive customers.

The solution is IPv6, a newer protocol with vastly more addresses — about 340 undecillion, which is a number so large it is difficult to comprehend. IPv6 addresses look completely different: they use hexadecimal notation and are much longer, like 2001:0db8:85a3:0000:0000:8a2e:0370:7334. The transition from IPv4 to IPv6 has been slow because it requires changes across the entire internet infrastructure.

For now, both systems run side by side. Your device might have both an IPv4 and an IPv6 address. Most websites and services still rely on IPv4, so you will encounter it far more often. Understanding IPv4 remains important because it is still how the vast majority of internet communication happens.

How to find your IPv4 address on different devices

On Windows, open the Command Prompt and type ipconfig. Look for "IPv4 Address" in the results. You will see both your private address (usually starting with 192.168 or 10.0) and information about your network connection.

On Mac, go to System Preferences, click Network, select your connection, and click Advanced. Your IPv4 address appears under the TCP/IP tab. On iPhone or iPad, go to Settings, tap Wi-Fi, and select your network — the IP Address field shows your private IPv4 address.

On Android, go to Settings, tap About Phone, and look for IP Address. On Linux, open a terminal and type hostname -I or ifconfig. To find your public IPv4 address from any device, search "what is my IP" in a web browser. The first result will show the address your internet service provider assigned to you.

What IPv4 addresses are used for beyond the internet

IPv4 addresses are not just for browsing the web. Your printer, smart TV, security camera, and other connected devices all need IPv4 addresses to communicate on your network. When you print a document, your computer sends it to your printer's IPv4 address. When you adjust your thermostat from your phone, the app is sending commands to the thermostat's IPv4 address.

Servers that host websites, email services, and cloud storage all have IPv4 addresses. When you visit a website, you are connecting to a server at a specific IPv4 address. The domain name you type (like google.com) is translated into an IPv4 address behind the scenes by a system called DNS, or Domain Name System. Without this translation, you would have to remember the IPv4 address of every website you wanted to visit.

Network administrators use IPv4 addresses to manage and troubleshoot networks. They can see which devices are connected, how much data each one is using, and whether any devices are behaving unusually. In business and large organizations, IPv4 addresses are essential for security, because access controls and firewall rules are often based on IP addresses.

Common misconceptions about IPv4 addresses

A common misunderstanding is that your IPv4 address reveals your exact location. It does not. Your public IPv4 address can be traced to your internet service provider and usually to your city or region, but not to your street address or home. Websites can see your public IP address, but they cannot see your private address or the specific device you are using.

Another misconception is that changing your IPv4 address will make you anonymous online. It will not. Your internet service provider knows which public address they assigned to you, and they can be compelled to reveal who that address belongs to. Websites also track you through cookies, login accounts, and other methods that have nothing to do with your IP address.

Some people think their IPv4 address is permanent. For most home internet users, it changes periodically. Your internet service provider can reassign it to someone else if you disconnect for a while, or they might change it as part of routine maintenance. Businesses and servers often pay for static IPv4 addresses that do not change, but this is not the default for residential internet.

Frequently Asked Questions

Can someone find out where I live from my IPv4 address?

Your public IPv4 address can be traced to your internet service provider and usually to your city or region, but not to your specific address. Websites can see your public IP, but they cannot determine your street address, home location, or which device in your home you are using. Your private IPv4 address is never visible to the outside internet.

Why do I have two different IPv4 addresses?

Your private IPv4 address is used only on your home or office network and is assigned by your router. Your public IPv4 address is assigned by your internet service provider and is used when you connect to the wider internet. Your router translates between them so devices on your network can communicate with the outside world.

What happens if two devices have the same IPv4 address?

If two devices on the same network have the same IPv4 address, they will not be able to communicate properly. Data meant for one device might go to the other, or both devices might stop working. This is called an IP conflict. Most modern routers prevent this by automatically assigning unique addresses, but it can happen if you manually configure addresses incorrectly.

Is IPv4 going away soon?

IPv4 is not disappearing anytime soon, even though IPv6 was created to replace it. Both systems run together on the internet today, and most devices and websites still use IPv4. The transition to IPv6 has been slow because it requires changes across the entire internet. You will likely encounter IPv4 for many years to come.

Can I choose my own IPv4 address?

On your home network, you can usually configure your device to use a specific private IPv4 address, but this requires manual setup and can cause problems if you choose an address already in use. Your router normally assigns addresses automatically, which is simpler and safer. Your internet service provider assigns your public IPv4 address, and you cannot choose it.