An IP address is a unique number that is used to identify a device on a network. This network could be the public internet, your work network, or your home Wi-Fi.
The IP address is “unique” within the context it’s used: on your local network, each device will need its own address; on the public internet, you need an address that is unique everywhere.
The “IP” part stands for Internet Protocol. The Internet Protocol is the set of rules that defines how data gets formatted, addressed, and routed between networks.
When you are sending information online, you aren’t sending a single big lump of data from sender to receiver. Instead, your information gets broken up into smaller chunks (called packets), labelled with information about the source and destination, and then sent through a series of networks until it reaches its final destination.
It’s the IP address and routing layer that makes all of this possible.
How an IP address works
Even though IP addressing is largely “behind the scenes”, the journey from typing a website name to seeing a page load follows a fairly consistent chain of events. Here’s a simple overview first, then a slightly more detailed explanation.
The high-level journey
- Your device connects to a network (home Wi-Fi, office network, mobile network).
- Your ISP/router assigns a private IP address (usually using DHCP for local/private addressing).
- DNS translates a web address into an IP for the destination server (turns example.com into a number).
- Data gets sent in packets from your device to the destination IP (each packet has source/destination IP info).
- Routers forward packets through the networks (using TCP/IP routing rules).
- Information is sent back to the source IP address (your device puts all the packets together and shows you the content).
Types of IP Addresses
People often talk about “types” of IP addresses in 4 main categories: public, private, static, and dynamic. These categories overlap – for example, you can have a public static IP or a public dynamic IP.
Public IP Address: A public IP address is the address that can be seen by the internet. It’s usually assigned by your ISP to your router (or to a device directly, depending on the setup).
Private IP Address: A private IP address is used inside your local network (home, office, school). Your router assigns a private IP address to devices so they can talk to each other and so the router can send traffic to the right device. When these devices access the internet, your router will use Network Address Translation (NAT) to translate these private addresses into the router’s public IP.
Common private ranges:
- 192.168.x.x (very common at home)
- 10.x.x.x (common in business networks)
- 172.16.x.x to 172.31.x.x (also used in business networks)
Static IP Address: A static IP address is one that does not change (or is intended not to change).
Static addresses can be configured:
- By an ISP at the public IP level (you pay for a fixed public IP)
- By a network admin at the private IP level (a device always gets the same private IP)
Dynamic IP Address: A dynamic IP address changes periodically. Most home broadband customers have dynamic public IPs. Inside your home network, private IPs are also typically dynamic (assigned by DHCP leases).
IPv4 vs IPv6: What’s the Difference?
IP addresses come in two main versions: IPv4 and IPv6. You’ll often hear this described as the internet “running out” of IPv4 addresses and moving toward IPv6.
IPv4: older, shorter, limited pool
IPv4 uses 32-bit addressing and is typically shown as four numbers separated by dots (dotted decimal notation), such as 203.0.113.42.
With 32 bits, IPv4 can support roughly 4.3 billion unique addresses in theory — and fewer in practice due to reserved ranges and allocations.
IPv6: newer, longer, enormous pool
IPv6 uses 128-bit addressing and is written in hexadecimal, grouped with colons (e.g., 2001:db8::1).
The IPv6 address space is so large it’s often described as effectively inexhaustible for practical purposes. That scale supports continued internet growth and can reduce the need for address-sharing workarounds.
Practical benefits of IPv6 include:
- More direct end-to-end addressing (less reliance on NAT)
- Improved routing efficiency in many cases
- Better long-term scalability
Final thoughts
IP addresses are the foundation of how networks communicate. They’re what make routing possible, support content delivery, and let devices all over the world exchange information reliably.
Understanding the basics – public vs private, static vs dynamic, IPv4 vs IPv6 – helps with connection troubleshooting, making better privacy choices, and working out how online services identify and interact with devices.
For more terminology and related concepts, the Canopius cyber glossary is a solid place to explore definitions in one place.
