Req 3e — Computer Networks

When you send a text to a friend across town or share a file with your patrol over Wi-Fi, you are using a computer network. Networks are the invisible highways that let devices share data, resources, and communication — and understanding how they work is fundamental to understanding the digital world.

What Is a Computer Network?

A computer network is two or more devices connected together so they can share data and resources. That is the simplest definition, and it covers everything from two laptops connected by a single cable to the billions of devices linked through the internet.

Networks need three things to function:

1. Devices (also called nodes or hosts) — computers, phones, printers, servers, or any hardware that sends or receives data
2. A connection medium — the physical or wireless link between devices (Ethernet cables, Wi-Fi radio waves, fiber-optic cables)
3. Protocols — shared rules that govern how data is packaged, addressed, sent, and received (the most common set is TCP/IP, which is the foundation of the internet)

LAN: Local Area Network

A Local Area Network (LAN) connects devices in a small, defined area — your home, a classroom, a Scout meeting hall, or a single building.

Characteristics of a LAN:

• Coverage: Small area — typically a single building or campus
• Ownership: Usually owned and managed by one person or organization (your family manages your home Wi-Fi; your school manages its network)
• Speed: Very fast — modern LANs typically run at 1 Gbps (gigabit per second) or higher over Ethernet, and 100+ Mbps over Wi-Fi
• Connection methods: Ethernet cables (wired) and Wi-Fi (wireless)
• Common equipment: Router, switch, access point

Everyday LAN examples:

• Your home Wi-Fi network connecting your phone, laptop, smart TV, and printer
• A school computer lab where all the desktops share one printer and internet connection
• A Scout camp office with a few computers networked together

WAN: Wide Area Network

A Wide Area Network (WAN) connects devices or networks across large geographic areas — cities, states, countries, or the entire globe. The internet itself is the largest WAN ever built.

Characteristics of a WAN:

• Coverage: Large area — city-wide, nationwide, or worldwide
• Ownership: Usually operated by telecommunications companies (ISPs like Comcast, AT&T, Verizon) or large organizations. No single entity owns the entire internet.
• Speed: Varies widely — from a few Mbps in rural areas to 10+ Gbps on fiber backbone connections
• Connection methods: Fiber-optic cables (including undersea cables), satellite links, cellular towers, microwave relays
• Common equipment: Routers, modems, fiber-optic switches, cellular towers

Everyday WAN examples:

• The internet — connecting billions of devices worldwide
• A company with offices in New York, London, and Tokyo connected through a private WAN
• Cellular data networks that let you use your phone anywhere with coverage

LAN vs. WAN at a Glance

How LANs and WANs Work Together

Here is what happens when you load a webpage:

1. Your laptop sends a request over your home LAN (via Wi-Fi to your router)
2. Your router forwards the request to your internet service provider through your WAN connection (cable, fiber, or DSL modem)
3. The ISP routes the request through the internet backbone (the global WAN) — possibly across undersea fiber-optic cables
4. The request reaches the web server (which is on its own LAN in a data center)
5. The server sends the webpage back along the reverse path

This entire round trip typically takes less than a second — even when the server is on another continent.

You have now covered all the fundamentals of digital data — how it is stored, compressed, processed, and transmitted. Time to move into the world of software and learn how the programs running on your devices actually work.