Network Engineering Basics – Part 4:

After learning about IP addresses and subnets, the next important step is understanding how networks are grouped and connected. Many beginners hear the terms LAN, WAN, and Internet used interchangeably. However, they are not the same thing.

In this article, we’ll clearly explain what LANs and WANs are, how the Internet fits in, and how data moves between them, using plain language and simple diagrams.

Why LAN, WAN, and Internet Matter

Before diving into definitions, it helps to understand why these distinctions exist. Networks are organized by size, distance, and purpose. As a result, engineers use different technologies and designs depending on whether traffic stays local or travels across the world.

Understanding these terms early makes everything else in networking much easier.

What Is a LAN (Local Area Network)?

A LAN, or Local Area Network, connects devices within a small, limited area.

Common examples include:

• A home network
• An office network
• A school or campus building

Because LANs cover short distances, they are typically:

• Fast
• Reliable
• Privately managed

Key takeaway:

A LAN connects nearby devices so they can communicate and share resources.

What Is a WAN (Wide Area Network)?

A WAN, or Wide Area Network, connects multiple LANs across large distances. Unlike LANs, WANs often span:

• Cities
• States
• Countries

For example, a company with offices in different cities uses a WAN to connect each office’s LAN.

Because of the distance involved, WANs are:

• Slower than LANs
• More complex
• Often provided by service providers

Key takeaway:

A WAN connects multiple local networks over long distances.

What Is the Internet?

The Internet is the largest WAN in the world. It connects millions of networks globally, including home LANs, business LANs, and provider WANs.

However, the Internet is not owned by one company. Instead, it is a massive collection of interconnected networks that agree to communicate using common standards.

Key takeaway:

The Internet connects many WANs and LANs into one global network.

LAN vs WAN vs Internet (Side-by-Side Comparison)

This comparison highlights why each network type exists.

How Data Moves Between LAN, WAN, and Internet

Now that you understand the differences, let’s see how traffic actually flows.

Step-by-Step Example

1. Your laptop sends data inside the LAN
2. The router checks the destination
3. If it’s outside the LAN, traffic goes to the WAN
4. If needed, traffic reaches the Internet
5. The response travels back the same way

Key takeaway:

Routers decide whether traffic stays local or travels outward.

Real-World Examples

Home User

• LAN: Devices in your house
• WAN: Your ISP connection
• Internet: Websites and streaming services

Business User

• LAN: Office network
• WAN: Links between offices
• Internet: Cloud services and customers

Seeing these examples makes the differences much clearer.

Common Beginner Confusion

Beginners often assume:

• Wi-Fi is the Internet
• LAN and Internet mean the same thing
• The router is the Internet

In reality, Wi-Fi is just one way to connect to a LAN, and the Internet exists far beyond your local network.

Why This Matters for Network Engineers

LAN, WAN, and Internet concepts affect:

• Network design
• Security boundaries
• Performance
• Troubleshooting

Therefore, understanding where traffic lives and travels is a core engineering skill.

What’s Next in the Series

Now that you understand how networks are grouped and connected, it’s time to focus on security.

This next article explains how firewalls protect LANs, WAN connections, and Internet traffic.

Final Thoughts

Although LAN, WAN, and Internet are often mentioned together, they serve very different roles. Once you understand the differences, networking concepts start to click into place.

This knowledge is another key building block in your network engineering journey.

Welcome back to Network Engineering Basics on Relay Rack 1.