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Computer networking is the practice of connecting computing devices so they can exchange data and share resources. From the internet you use every day to the Wi-Fi in your home, networking is the invisible fabric that ties the digital world together.
Networking underpins virtually every modern technology:
| Domain | How Networking is Used |
|---|---|
| Cloud computing | Data centres communicate via high-speed networks |
| Web applications | Browsers fetch pages from servers using HTTP/HTTPS |
| Video streaming | Content is delivered via CDN networks globally |
| Online gaming | Low-latency connections keep gameplay responsive |
| IoT | Smart devices communicate over Wi-Fi, Bluetooth, and cellular |
| Remote work | VPNs and video conferencing rely on stable networks |
| E-commerce | Secure transactions depend on encrypted network protocols |
Networks are classified by their size and scope:
| Type | Full Name | Description | Example |
|---|---|---|---|
| PAN | Personal Area Network | Connects devices within a few metres | Bluetooth headset to phone |
| LAN | Local Area Network | Connects devices in a building or campus | Office Wi-Fi network |
| MAN | Metropolitan Area Network | Spans a city or large campus | City-wide fibre backbone |
| WAN | Wide Area Network | Spans countries or continents | The Internet itself |
| WLAN | Wireless LAN | A LAN using wireless technology | Home Wi-Fi network |
The topology describes how devices are arranged and connected:
| Topology | Description | Pros | Cons |
|---|---|---|---|
| Star | All devices connect to a central switch/hub | Easy to manage, one failure does not affect others | Central device is a single point of failure |
| Bus | All devices share a single communication line | Simple and cheap | Hard to troubleshoot, one break takes down the segment |
| Ring | Devices form a circular chain | Predictable performance | One device failure can disrupt the ring |
| Mesh | Every device connects to every other device | Highly redundant and fault-tolerant | Expensive and complex |
| Hybrid | Combination of topologies | Flexible | Can be complex to design |
Most modern networks use a star or hybrid topology.
Star Topology:
[PC1] [PC2]
\ /
[Switch]
/ \
[PC3] [PC4]
Mesh Topology:
[A]------[B]
| \ / |
| \/ |
| /\ |
| / \ |
[C]------[D]
Data is not sent as one continuous stream. Instead, it is broken into small units called packets:
| Term | Definition | Analogy |
|---|---|---|
| Bandwidth | The maximum amount of data that can be transmitted per second | Width of a motorway |
| Latency | The time it takes for a packet to travel from source to destination | Speed limit on the motorway |
| Throughput | The actual data transfer rate achieved | Actual traffic flow |
Example: A 100 Mbps connection (bandwidth) with 20 ms latency means you can transfer up to 100 megabits per second, but each individual packet takes at least 20 milliseconds to arrive.
A protocol is a set of rules that governs how data is transmitted and received. Without protocols, devices would not understand each other.
| Protocol | Purpose |
|---|---|
| TCP | Reliable, ordered delivery of data |
| UDP | Fast, connectionless delivery (no guarantee) |
| IP | Addressing and routing packets across networks |
| HTTP/HTTPS | Web page requests and responses |
| DNS | Translating domain names to IP addresses |
| DHCP | Automatically assigning IP addresses to devices |
| FTP | File transfers |
| SSH | Secure remote shell access |
We will explore each of these protocols in detail throughout this course.
To manage the complexity of networking, engineers use layered models that separate concerns into distinct layers:
| Model | Layers | Purpose |
|---|---|---|
| OSI Model | 7 layers | A theoretical reference model for understanding networking |
| TCP/IP Model | 4 layers | The practical model used by the Internet |
OSI Model TCP/IP Model
┌─────────────┐
│ Application │
├─────────────┤ ┌─────────────┐
│ Presentation│ │ Application │
├─────────────┤ ├─────────────┤
│ Session │ │ Transport │
├─────────────┤ ├─────────────┤
│ Transport │ │ Internet │
├─────────────┤ ├─────────────┤
│ Network │ │ Network │
├─────────────┤ │ Access │
│ Data Link │ └─────────────┘
├─────────────┤
│ Physical │
└─────────────┘
We will cover these models in depth in the next two lessons.
Computer networking is the foundation of our connected world. It involves connecting devices so they can exchange data using agreed-upon protocols. Networks vary in size from PANs to WANs, can be arranged in different topologies, and rely on layered models (OSI and TCP/IP) to organise the complexity. In the following lessons, we will dive into the OSI model, TCP/IP, IP addressing, DNS, HTTP, routing, network devices, troubleshooting, and cloud networking.