In this lesson, you'll explore the fundamentals of the internet and web technologies, which are essential for understanding how information is shared and accessed online. You'll learn about the differences between the internet and the World Wide Web (WWW), the client-server model, key protocols like HTTP, TCP, IP, and VOIP, and the infrastructure that powers the web. To make it practical, you'll use MakeCode for the micro:bit to simulate simple network communication.

Here's what you'll cover:

1. Understanding the internet and the WWW.
2. Exploring the client-server model.
3. Learning about key protocols: HTTP, TCP, IP, and VOIP.
4. Examining web infrastructure.
5. Practical activity: Simulating a simple client-server interaction using micro:bit radio to send messages, mimicking VOIP-like communication.
6. Discussing the importance and applications of these technologies.

The internet is a global network of interconnected computers and devices that communicate with each other using standardised protocols. It's like a vast system of roads connecting cities worldwide, allowing data to travel from one point to another.

The World Wide Web (WWW), often just called the web, is a service that runs on the internet. It's a collection of interconnected documents and resources, accessed via hyperlinks and URLs. Think of the internet as the underlying infrastructure (the roads), and the WWW as the vehicles and destinations (websites, pages) that use those roads.

Key differences:

• The internet enables communication between devices (e.g., email, file transfer).
• The WWW is specifically for browsing hyperlinked content using web browsers.

Without the internet, there would be no WWW, but the internet supports many other services beyond the web, like streaming or online gaming.

The client-server model is a fundamental concept in networking where tasks are divided between clients and servers.

A client is a device or program that requests services or resources, like your web browser asking for a webpage.

A server is a powerful computer that provides those resources, such as a web server sending webpage data back to your browser.

How it works:

1. The client sends a request to the server (e.g., typing a URL).
2. The server processes the request and sends a response (e.g., the webpage content).
3. This model allows efficient resource sharing and centralised data management.

Examples: When you load a website, your computer (client) communicates with the site's server.

A protocol is a set of established rules and standards that dictate how data is transmitted and received between devices in a network. It's like a common language or a agreed-upon etiquette that ensures all devices can communicate effectively without misunderstandings, defining everything from how data is formatted to how errors are handled. Without protocols, devices wouldn't know how to interpret the data they receive. Here are some important ones:

• HTTP (HyperText Transfer Protocol): Used for transferring web pages. It's the foundation of data communication on the WWW. When you visit a site, HTTP handles the request and response.
• TCP (Transmission Control Protocol): Ensures reliable data transmission by breaking data into packets, sending them, and reassembling them at the destination. It checks for errors and resends lost packets.
• IP (Internet Protocol): Handles addressing and routing of packets across networks. Every device has an IP address, like a postal address for data.
• VOIP (Voice Over Internet Protocol): Allows voice communication over the internet, like in video calls (e.g., Zoom). It converts voice into digital packets sent via IP.

These protocols work together: IP routes packets, TCP ensures reliability, HTTP handles web content, and VOIP manages voice data.

Web infrastructure refers to the hardware and software that support the internet and WWW. It's the backbone that enables data to be stored, processed, and transmitted across the globe, making sure everything from websites to online videos loads quickly and reliably.

Key components:

• Servers and Data Centres: These are powerful computers and large facilities that store and process vast amounts of data. For example, when you watch a video on YouTube, the data is retrieved from Google's data centres.
• Routers and Switches: These devices direct data traffic, deciding the best path for information to travel from one point to another, much like traffic lights and signs on a road network.
• Cables and Wireless Networks: The physical connections include undersea fibre optic cables for long-distance data transfer and wireless technologies like Wi-Fi or 5G for local access, ensuring data can move wired or wirelessly.
• Domain Name System (DNS): This acts like a phonebook for the internet, translating easy-to-remember domain names (e.g., google.com) into numerical IP addresses that computers use to locate each other.

This infrastructure works together to ensure data travels efficiently from servers to clients worldwide, supporting everything from social media to online shopping.