Lesson 1 of 13
What is a Network?
How billions of devices talk to each other⏱ ~2 min
A city has roads connecting every building. A network has cables (or WiFi) connecting every device. Just like a postal system needs addresses to deliver mail, a network needs IP addresses to deliver data. Your home WiFi is a tiny city — your phone, laptop, TV, and game console are all buildings on the same block.
Types of Networks
- ›🏠 LAN (Local Area Network) — your home or school. High speed, privately owned.
- ›🏢 MAN (Metropolitan Area Network) — covers a city, like a university campus spread across buildings.
- ›🌍 WAN (Wide Area Network) — spans countries. Your ISP connects you to the WAN.
- ›🌐 The Internet — literally a network of networks. Nobody owns it — millions of networks connected together.
The Key Players
- ›📡 Router — the post office. Decides which path data takes between networks.
- ›🔀 Switch — the office receptionist. Connects devices inside the same network and directs traffic intelligently.
- ›🔒 Firewall — the security guard. Checks every packet and blocks suspicious ones.
- ›📶 Access Point — extends WiFi coverage (like WiFi repeaters in big houses).
As of 2024, over 15 billion devices are connected to the internet — more than double the number of humans on Earth. By 2030, estimates put that number at 30 billion.
Every device on a network is a potential entry point for attackers. The more devices on a network, the larger the 'attack surface.' This is why hospitals, schools, and companies spend so much on network security.
Quick Check
Your school has computers in 5 classrooms all connected to one central switch. What type of network is this?