Your PC has one address, your router shows another to the world, and websites see a third party entirely. This page untangles public vs private addresses and the translation trick — NAT — that lets a whole office share one public address.
'My PC says 192.168.1.25, but the website says my IP is 49.something — which one is real?' Both. They are addresses in two different worlds, and the border between those worlds is where NAT works.
☝️ The internet sees only the router's public address. Every inside device is hidden behind it and translated by NAT.
A private IP works only inside your building: 192.168.x.x, 10.x.x.x and 172.16–31.x.x. A public IP works on the whole internet and is assigned by your internet provider to your router. Every website you open sees the public one — never your PC's private address.
This is why the same private address, 192.168.1.25, can exist in your office and in a home across the city at the same time. Private streets are not part of the world's map; each building draws its own.
If inside devices are invisible to the internet, how does a reply ever find the right PC? That is NAT (Network Address Translation), a job your router does non-stop. When your PC sends a request out, the router rewrites the return address to its own public IP and notes: this conversation belongs to 192.168.1.25. When the reply comes back, the note tells the router which inside device gets it.
Twenty devices can browse at once through one public address because the router keeps twenty separate notes. From the internet's side, the whole office looks like a single user — the router.
One honest twist: many providers now place their own NAT in front of your router (called CGNAT). Then even your router's 'public' address is private on the provider's network, and your true public address is shared with other customers. Port forwarding and some remote-access setups stop working in this situation, while normal browsing never notices. If remote access suddenly fails on a new connection, CGNAT is a prime suspect — only your provider can confirm it.
Watch the video for the full inside-outside picture, then check your own public IP from two different PCs — same answer, now you will know why.
▶️ Watch Full VideoA private IP (like 192.168.1.25) works only inside your own network. A public IP is assigned by your internet provider to your router and is the address the internet sees. All your inside devices share that one public address through NAT.
Because the website can only see the public address of your router. Your PC's private address stays inside the building — the router translates between the two. Every PC in your office will show the same public IP on that website.
NAT is the router's translation and note-keeping job. It sends your requests out under its own public address, remembers which inside device each conversation belongs to, and delivers replies back correctly. It lets many private devices share one public address.