Welcome to Networking & Internet Basics!

Hey there! Ready to dive into the amazing world of how computers talk to each other? This chapter is all about the magic that connects your phone to TikTok, your computer to Google, and your game console to your friends online. It's called networking!

Understanding these basics is super important because the internet and networks are everywhere. By the end of this, you'll understand how it all works, from the cables in the wall to the Wi-Fi in the air. Let's get started!


1. What is a Computer Network? (LANs vs. WANs)

A computer network is simply two or more computers connected together so they can share information and resources (like printers or an internet connection). The two main types you need to know are LAN and WAN. Think of it like talking to people: a LAN is a chat in a small room, while a WAN is a phone call to another country!

Local Area Network (LAN)

A LAN connects devices over a small geographical area. It's the network you have at home, in your school's computer lab, or within a single office building.

  • Scope: Small area (e.g., a single building).
  • Speed: Usually very fast because the distances are short.
  • Ownership: Privately owned and managed (e.g., your family owns your home network, your school owns the school network).

Wide Area Network (WAN)

A WAN connects devices over a large geographical area, like across cities, countries, or even continents. A WAN is often a network of many LANs connected together.

  • Scope: Large area (e.g., connecting offices in Hong Kong and London).
  • Speed: Generally slower than a LAN because data has to travel much further.
  • Ownership: Often managed by several organisations or telecommunication companies.

The biggest WAN in the world is the Internet!

Key Takeaway: LAN vs. WAN

The easiest way to remember the difference is the location. If it's in one building, it's a LAN. If it connects different locations far apart, it's a WAN. Simple as that!


2. What Can We Do on a Network? (Network Services)

So, why do we even bother connecting computers? Because it lets us do cool and useful stuff! These are called network services.

Resource Sharing

This is one of the biggest benefits! Instead of everyone needing their own expensive equipment, we can share.

  • File Sharing: You can access files stored on a central computer called a server. Think of Google Drive or accessing files on your school's network.
  • Hardware Sharing: An entire office can share one single printer or scanner. This saves a lot of money!
  • Internet Connection Sharing: Your home router shares one internet connection with your phone, laptop, and TV all at the same time.

Internal Communications and Conferencing

Networks make it incredibly easy to communicate.

  • Communication: Sending emails or instant messages to people within the same network.
  • Conferencing: Holding video or voice calls with colleagues in different rooms or even different buildings connected by the network.
Key Takeaway: Network Services

Networks are all about sharing and communicating efficiently. They save money, time, and make collaboration much easier.


3. The Building Blocks: Network Hardware

To build a network, you need some physical equipment. Think of it like building with LEGOs – you need the right pieces to make everything connect.

Communication Links (The Roads for Data)

This is how data physically travels from one place to another.

  • Unshielded Twisted Pair (UTP) Cable: This is your standard Ethernet cable. It's common, cheap, and used for most wired LANs.
  • Fibre Optic Cable: Uses tiny strands of glass and sends data as pulses of light. It's extremely fast and can carry huge amounts of data, but it's more expensive. It's often used for the backbone of the internet.
  • Wireless (Microwave, Satellite): Uses radio waves to send data through the air. Microwaves are used for connecting buildings across a city, while satellites are used for very long distances, like across oceans.

Key Network Devices

These devices help manage and direct the flow of data on the network.

  • Network Interface Card (NIC): The "doorway" or "port" on your computer that lets you plug in a network cable or connect to Wi-Fi. Every device on a network needs one.
  • Modem: Short for MOdulator-DEModulator. Its job is to translate signals. It converts the digital signals from your computer into analog signals that can travel over the phone or cable lines, and vice-versa. It connects your LAN to the Internet (a WAN).
  • Switch: A smart device used inside a LAN. When a computer sends data, the switch knows exactly which other computer on the LAN to send it to. It's like a smart traffic cop that sends cars directly to the right house on a street.
  • Router: A device that connects different networks together. Your home router's main job is to connect your home LAN to the internet (the giant WAN). It's like a post office that figures out the best path to send your mail to another city.
Quick Review: Switch vs. Router

This can be confusing, so here's a simple way to remember it:
- A Switch connects devices within ONE network (e.g., computers and a printer in an office).
- A Router connects DIFFERENT networks together (e.g., your home network to the Internet).


4. Going Wireless: Key Wi-Fi Concepts

Wireless networks (WLANs) are super convenient. Here are a few key ideas about how they work.

  • Frequency: Wi-Fi uses radio waves at specific frequencies, most commonly 2.4 GHz and 5 GHz. Think of these like different radio station channels. 5 GHz is faster but has a shorter range.
  • Bandwidth: This is a measure of how much data can be sent over the connection at one time. Higher bandwidth means a faster connection. Think of it as the number of lanes on a highway – more lanes mean more cars can travel at once.
  • Interference: Wireless signals can be disrupted by other electronic devices, like microwave ovens, or even other Wi-Fi networks nearby. This can slow down your connection.
  • Roaming: This is the ability to move from one Wi-Fi coverage area (access point) to another without losing your connection. Your phone does this automatically at school as you walk from the classroom to the library.
Did you know?

The name "Wi-Fi" doesn't actually stand for anything! It was a marketing name created to sound catchy, like "Hi-Fi" (High Fidelity) for audio.


5. How We Connect to the Internet

There are many ways to get online, each with its own pros and cons.

Comparing Internet Access Methods

Let's compare two common methods based on what matters most: speed, cost, security, and availability.

Broadband (Fibre-to-the-Home)

  • Speed: Very high and stable. Great for streaming 4K movies and gaming.
  • Cost: Monthly fee is fixed, but setup can sometimes be expensive.
  • Security: Generally very secure, as it's a private connection to your home.
  • Availability: Widely available in cities and residential areas, but may not be available in remote villages.

Mobile Data (4G / 5G)

  • Speed: Can be very fast (especially 5G), but can vary depending on your location and how many people are using it.
  • Cost: Depends on your data plan. Can be expensive if you use a lot of data.
  • Security: Reasonably secure, but you still need to be careful.
  • Availability: Very high. You can get online almost anywhere you have a mobile signal.
Key Takeaway: Choosing a Connection

For home use where speed and stability are key, Broadband is usually best. For getting online when you're out and about, Mobile Data is the winner.


6. The Rules of the Road: Protocols & Software

For millions of computers made by different companies to communicate perfectly, they all need to follow the same set of rules. These rules are called protocols. Don't worry if this sounds tricky at first, the main idea is simple!

Communications Software

This is the software you use to interact with the network, like a web browser (Chrome, Safari) to surf the web or an email client (Outlook, Gmail) to send messages.

Communication Protocols (TCP/IP)

The most important set of protocols for the internet is the TCP/IP suite. Think of TCP and IP as two workers with different jobs who team up to get your data delivered.

IP (Internet Protocol) and IP Addresses

The IP's job is all about addressing and routing. Every single device connected to the internet needs a unique address, called an IP address. It’s just like a mailing address for your house.

  • IPv4: The older version. It looks like this: 192.168.1.1. There are only about 4 billion IPv4 addresses, and we have run out!
  • IPv6: The new version, created to solve the address shortage. It looks like this: 2001:0db8:85a3:0000:0000:8a2e:0370:7334. There are so many IPv6 addresses that we will never run out.

Memory Aid: Think v4 = 4 numbers, v6 = a lot more numbers and letters!

TCP (Transmission Control Protocol)

The TCP's job is to make sure the data is sent reliably and in the correct order.

Here’s how TCP and IP work together, step-by-step:
1. When you send a message, TCP breaks it into small pieces called packets.
2. TCP numbers each packet so they can be reassembled in the right order at the destination.
3. IP adds the sender's and receiver's IP addresses to each packet (like putting an address on an envelope).
4. The packets are sent over the internet. They might even take different routes to get there!
5. At the receiving end, TCP checks if all the packets have arrived. If any are missing or damaged, it requests for them to be sent again.
6. Once all packets are there, TCP puts them back together in the correct order to remake the original message.

Key Takeaway: TCP/IP Teamwork

Think of it like sending a book in the mail.
- TCP is the person who carefully tears the book into numbered pages (packets) and then reassembles it at the other end, checking that no pages are missing.
- IP is the postal service that delivers each individual page to the correct mailing address.
Together, they make sure your data gets where it needs to go, complete and correct!