What is an IP address?

What is an IP address?

An IP address (Internet Protocol address) is a unique numerical identifier assigned to every device connected to a computer network that uses the Internet Protocol for communication. Think of it as the digital equivalent of your home's mailing address — it tells other devices on the internet exactly where to send information intended for your computer, smartphone, or other connected device.

The term "IP address" stands for Internet Protocol address, where "Internet Protocol" refers to the set of rules that govern how data is sent and received over the internet. Every email you send, every web page you visit, and every video you stream relies on IP addresses to ensure the data reaches the right destination.

The basic function of IP addresses

IP addresses serve two primary functions in networking:

1. Identification. They uniquely identify a device on a network.
2. Location addressing. They provide the location of the device in the network.

When you type a website address like google.com into your browser, your device uses the Domain Name System (DNS) to translate that human-readable name into an IP address like 172.217.14.78. Your computer then uses this IP address to connect directly to Google's servers.

Real-world analogy. Imagine the internet as a massive city with millions of buildings (devices). Each building needs a unique street address (IP address) so that mail carriers (data packets) can deliver letters (information) to the correct destination. Without addresses, it would be impossible to ensure that mail reaches the right recipient.

How IP addresses work

Understanding how IP addresses work requires looking at the internet as a network of networks. When you connect to the internet, your Internet Service Provider (ISP) assigns your device an IP address, either temporarily (dynamic) or permanently (static).

The communication process

Here's what happens when you visit a website:

1. Request initiation. You type a web address in your browser.
2. DNS translation. Your device asks a DNS server to translate the domain name to an IP address.
3. Route discovery. Your device finds the best path to reach the destination IP address.
4. Data transmission. Data packets are sent from your IP address to the website's IP address.
5. Response delivery. The website sends data back to your IP address.

This entire process typically happens in milliseconds, making the internet feel instant despite the complex routing that occurs behind the scenes. Want to see what your IP reveals right now? Try our IP lookup tool.

IPv4 vs IPv6: understanding the difference

There are currently two versions of IP addresses in use: IPv4 (Internet Protocol version 4) and IPv6 (Internet Protocol version 6). Understanding the difference between these two systems is crucial for anyone looking to understand modern networking.

IPv4 addresses

IPv4 addresses are the traditional format that most people recognise. They consist of four numbers separated by periods, with each number ranging from 0 to 255. For example: 192.168.1.1 or 8.8.8.8.

• 32-bit addresses — approximately 4.3 billion unique addresses.
• Dotted decimal notation — easy for humans to read and remember.
• Address exhaustion — we've nearly run out of available IPv4 addresses.
• Widespread compatibility — supported by all internet-connected devices.

IPv6 addresses

IPv6 addresses were developed to solve the IPv4 address shortage. They use a much longer format with eight groups of four hexadecimal digits separated by colons. For example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334.

• 128-bit addresses — approximately 340 undecillion unique addresses.
• Hexadecimal notation — more compact but complex for humans.
• Virtually unlimited addresses — enough for every grain of sand on Earth.
• Improved security — built-in encryption and authentication features.

Public vs private IP addresses

Not all IP addresses are created equal. There's an important distinction between public and private IP addresses that affects how devices communicate on networks.

Public IP addresses

A public IP address is globally unique and routable on the internet. It's assigned by your Internet Service Provider (ISP) and is visible to websites and services you connect to online.

• Globally unique — no two devices on the internet share the same public IP.
• ISP assigned — your internet provider manages your public IP address.
• Internet accessible — can be reached directly from anywhere on the internet.
• Geo-locatable — can be traced to a general geographic location.

Private IP addresses

A private IP address is used within local networks (like your home or office) and cannot be accessed directly from the internet. These addresses are reused across different private networks without conflict.

Common private IP address ranges:

• Class A: 10.0.0.0 to 10.255.255.255
• Class B: 172.16.0.0 to 172.31.255.255
• Class C: 192.168.0.0 to 192.168.255.255

Home network example. In your home, your router might have a public IP address like 98.207.254.136 assigned by your ISP. Inside your home network, your devices use private addresses like 192.168.1.100 (laptop), 192.168.1.101 (phone), and 192.168.1.102 (smart TV). Your router acts as a translator between the public and private networks using Network Address Translation (NAT).

Static vs dynamic IP addresses

IP addresses can be assigned in two ways: statically (permanently) or dynamically (temporarily). Understanding this distinction is important for both home users and businesses.

Dynamic IP addresses

Dynamic IP addresses are temporarily assigned to your device by your ISP or local network. These addresses can change periodically, typically when you restart your modem or after a certain time period.

• Cost-effective — ISPs can reuse addresses efficiently.
• Automatic configuration — no manual setup required.
• Enhanced privacy — your IP address changes periodically.
• Efficient allocation — addresses are only used when needed.

Static IP addresses

Static IP addresses are permanently assigned to a device and never change. They're typically used for servers, websites, and devices that need consistent accessibility.

• Consistent connectivity — always reachable at the same address.
• Server hosting — essential for running web servers or services.
• Remote access — easier to connect to devices remotely.
• DNS stability — domain names can point to consistent IP addresses.

Most home internet users have dynamic IP addresses, while businesses and web servers typically use static IP addresses for reliability and accessibility.

How to find your IP address

There are several ways to find your IP address, depending on whether you want to find your public or private IP address and what device you're using.

Finding your public IP address

1. Use our IP lookup tool — visit check.systems/ip.php and your IP address will be displayed immediately.
2. Google search — simply search "what is my IP" in Google.
3. Command line — use curl ifconfig.me in terminal or command prompt.
4. Router interface — log into your router to see the WAN IP address.

Finding your private IP address

Windows:

1. Open Command Prompt (cmd).
2. Type ipconfig and press Enter.
3. Look for "IPv4 Address" under your network adapter.

Mac/Linux:

1. Open Terminal.
2. Type ifconfig or ip addr show.
3. Look for your network interface's inet address.

Mobile devices. On smartphones and tablets, you can usually find your private IP address in the Wi-Fi settings, under the connected network's details.

IP address security and privacy

Your IP address can reveal more information about you than you might expect. Understanding the security and privacy implications is crucial in today's digital world.

What your IP address reveals

When you browse the internet, your public IP address can provide the following information:

• Geographic location — city, region, and country (usually accurate to city level).
• Internet Service Provider — your ISP and connection type.
• Organisation — if you're browsing from work or school.
• Time zone — based on your geographic location.
• Proxy usage — whether you're using a VPN or proxy service.

Privacy concerns

While IP addresses don't directly reveal personal information like your name or exact address, they can be used for:

• Tracking — websites can track your browsing behaviour across sessions.
• Geo-blocking — restricting content based on your location.
• Targeted advertising — showing ads relevant to your geographic location.
• Legal investigations — ISPs can link IP addresses to customer accounts.

Protecting your IP address

• VPN services — route your traffic through encrypted tunnels.
• Proxy servers — act as intermediaries between you and websites.
• Tor browser — uses multiple layers of encryption and routing.
• Public Wi-Fi — use different networks to change your apparent location.

The future of IP addressing

As we move further into the digital age, IP addressing continues to evolve. Understanding current trends helps prepare for the future of internet connectivity.

IPv6 adoption

While IPv4 remains dominant, IPv6 adoption is accelerating due to several factors:

• Address exhaustion — IPv4 addresses are nearly depleted globally.
• IoT growth — Internet of Things devices need massive numbers of IP addresses.
• Mobile expansion — smartphone growth in developing countries drives demand.
• Network efficiency — IPv6 offers better routing and reduced overhead.

Emerging technologies

• 5G networks — enable massive IoT deployments requiring IPv6.
• Edge computing — distributes IP address management to network edges.
• Software-defined networking — enables dynamic IP address allocation.
• Blockchain networking — explores decentralised IP address management.

What this means for users

• Seamless connectivity — dual-stack implementations ensure compatibility.
• Enhanced security — IPv6's built-in security features become standard.
• Better performance — more efficient routing reduces latency.
• Device proliferation — every device can have a unique global address.

Related reading: IP addresses explained simply · IP addressing & subnetting · Bogon addresses & invalid IP ranges