Private and Public IP Addresses
If every device in the world needed its own unique IP address, we would have run out of addresses long ago. The solution? A clever system of private and public addresses.
Think of an apartment building. The building has one street address that the postal service uses. But inside, each apartment has its own number — 1A, 2B, 3C. The internal numbering only matters within the building.
Networks work similarly.
Private IP Addresses
Inside your home or office network, devices get private IP addresses. These typically look like:
192.168.1.x
192.168.0.x
10.0.0.x
172.16.x.x
These addresses only have meaning within your local network. Your laptop might be 192.168.1.5, your phone 192.168.1.6, and your smart TV 192.168.1.7. But these same addresses are used in millions of other homes — they're not globally unique.
Public IP Addresses
Your router has a public IP address assigned by your internet provider. This address is unique on the internet and represents your entire household to the outside world.
When you visit a website, the website sees your public IP address — not the private address of your specific device.
How They Work Together
Your router performs Network Address Translation (NAT) to bridge these two worlds. When your laptop requests a webpage, the router:
- Receives the request from your laptop's private address
- Sends it out using the public address
- Remembers which internal device made the request
- Routes the response back to the correct device
This is like a receptionist at a company. Calls come in to one main number, and the receptionist forwards them to the right extension internally.
Why This Matters
Understanding private vs public addresses helps you:
- Troubleshoot network issues
- Understand why you can't directly access devices on someone else's network
- Configure home network settings
- Grasp basic network security concepts