Computer Networks Basics·Lesson 9 of 10
Intranet vs Internet vs Extranet
Three Scopes of Access
PAN, LAN, MAN, and WAN classify networks by size. Intranet, internet, and extranet classify them by who's allowed in. The three sound similar but describe very different levels of access: fully public, strictly private, and a controlled middle ground for trusted outsiders.
An office building
The public street outside is the internet — anyone can walk it. The staff-only offices inside are the intranet — you need to work there to enter. The visitor lounge, reachable only with a guest badge, is the extranet — outsiders get in, but only to a limited area.
The Internet
The internet is the public, global network of networks — open to anyone with a connection. It's built on shared standards so any device, anywhere, can reach any other. When you browse a website or send an email across companies, you're using the internet.
The Intranet
An intranet is a private network that belongs to a single organization. It uses the same underlying technology as the internet, but access is restricted to members — employees, students, or staff. Company wikis, internal dashboards, and HR portals typically live on an intranet, invisible to the outside world.
The Extranet
An extranet extends part of an intranet to specific, trusted outsiders — partners, suppliers, or clients — usually over a secure connection like a . It's a controlled bridge: outsiders get access to just the resources they need (like a shared order system) without being let into the whole internal network.
Side by Side
| Access | Who can use it | Example | |
|---|---|---|---|
| Internet | Public | Anyone | Browsing any website |
| Intranet | Private | One org's members | Internal company wiki |
| Extranet | Controlled | Org + trusted partners | Supplier order portal |
How they relate
An extranet is essentially an intranet that selectively opens a door to outsiders. All three can run over the same physical infrastructure — the difference is who is authorized, enforced by authentication and access controls, not by separate wires.
“"The internet and the World Wide Web are the same thing."”
Q:What's the key difference between an intranet and an extranet?
A: An intranet is private to one organization's own members. An extranet extends limited, controlled access to trusted outsiders like partners or suppliers — the same private network, but with a secure door opened to specific external users.
Quick Revision Cheat Sheet
Internet: Public — open to anyone, global
Intranet: Private — one organization's members only
Extranet: Controlled — intranet opened to trusted partners
What differs: Who is authorized, not the physical wires
Internet ≠ Web: The Web is one service running on the internet