# Computer Networks

Part of the Digital Technology Merit Badge Digital Resource Guide: [Introduction & Overview](https://merit-badge.university/merit-badges/digital-technology/guide/index.md)

*3. How Digital Data Works*

> **3e.** Explain what a computer network is and the difference between a local area network (LAN) versus a wide area network (WAN).

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

> **Tip**
>
> When you connect to your home Wi-Fi, you are joining a LAN. Every device on that network can potentially see and communicate with every other device. That is how your phone can send a document to your wireless printer — they are on the same LAN.

## 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

![Network diagram showing two houses with devices connected via LAN routers, linked through the internet WAN cloud](https://ik.imagekit.io/doulacoop/tr:w-800/mbu-assets/merit-badges/digital-technology/guide/lan-vs-wan-diagram?v=97bd9287)

## LAN vs. WAN at a Glance

| Feature | LAN | WAN |
|---------|-----|-----|
| **Area covered** | Single building or campus | Cities, countries, worldwide |
| **Owned by** | Individual or single organization | Telecom providers or shared infrastructure |
| **Speed** | Very high (1–10 Gbps typical) | Varies (10 Mbps to 10 Gbps) |
| **Cost** | Low (your router costs ~$50–$200) | High (undersea cables cost hundreds of millions) |
| **Example** | Your home Wi-Fi | The internet |
| **Latency** | Very low (under 1 ms) | Higher (10–100+ ms depending on distance) |

## 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.

> **Did You Know?**
>
> Over 550 undersea fiber-optic cables crisscross the ocean floor, carrying more than 99% of intercontinental internet traffic. Some of these cables are over 20,000 kilometers long and sit on the ocean floor up to 8,000 meters deep. They carry data at the speed of light — literally.

[Submarine Cable Map](https://www.submarinecablemap.com/): An interactive map showing every undersea internet cable in the world — zoom in to see the cables that connect continents and carry the internet's data.

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.

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