Lesson video

Hello, my name is Mrs. Holborow, and welcome to Computing.

I'm so pleased you've decided to join me for the lesson today.

In today's lesson, we're going to be investigating the hardware and software that support the World Wide Web, and we will see how data is transmitted across the internet.

Welcome to today's lesson from the unit "The internet and web technologies." This lesson is called "How data travels across the internet." And by the end of today's lesson, you'll be able to explain how the components of the World Wide Web work together to display web pages.

Shall we make a start? We will be exploring these keywords in today's lesson.

Let's take a look at them now.

Domain name system, or DNS, domain name system, servers that work together to match domain names to the stored location of a web page.

Data packet, data packet, a small part of the whole file that is transmitted over a network.

Packet switching, packet switching, a method of transmitting data across the internet using small packets of data.

Look out for these keywords throughout today's lesson.

Today's lesson is divided into two sections.

We'll start by describing how hardware and software support the World Wide Web.

We'll then move on to explain how data is transmitted using data packets.

Let's make a start by describing the hardware and software which supports the World Wide Web.

Aisha says, "My internet cut out last night.

None of the websites would load, it was so frustrating." Have you ever been in that situation? It is frustrating, isn't it? Alex says, "Yeah, it's easy to forget how much needs to work just to get online." Aisha says, "True.

It's not just the device, is it?" Alex says, "There's a whole setup behind it.

Hardware, software, networks, all working together." Aisha says, "I should probably know how all that fits together." Alex says, "Once you understand it, it's easier to spot problems, and it's actually kind of cool seeing how it all connects." Aisha says, "This feels like something I should know more about, especially because I use it every day." Alex says, "I agree, Aisha.

The more you know, the easier it will be to troubleshoot." Troubleshoot means to solve problems. The World Wide Web, or WWW, relies on hardware and software to deliver information and services.

Client devices are what people use to access the internet and browse the web.

These include laptops, tablets, and smartphones.

Client devices use software to send requests to websites.

When you type in a web address, the device contacts a server to load the web page.

The device receives and displays information like text, images, and videos from websites.

Network devices connect client devices to the internet and manage how data is sent and received.

Common network devices include modems, routers, and switches.

A modem connects your home or business to the internet via your internet service provider, or ISP.

Routers direct internet traffic and connect multiple devices to the network, often using Wi-Fi.

So at home, you might have a router that is used to connect your smartphone, your laptop, or your tablet to the internet.

Switches are used in wireless networks and connect multiple devices, like in schools or offices, and manage local network traffic.

Servers are powerful computers that store and manage websites and online services.

They respond to requests from client devices.

They host web content, so HTML pages, images, videos, and databases.

When you access the website, your device is retrieving data from a server somewhere in the world.

Transmission media are the physical or wireless ways data travels across the internet.

Cables, for example, fibre optic or Ethernet, provide fast, reliable internet connections, especially in buildings.

Wi-Fi allows wireless devices to connect to the internet via a router.

Mobile networks, like 3G, 4G, and 5G, enable smartphones and tablets to access the web without Wi-Fi using mobile phone masts.

Time to check your understanding.

I have a question for you.

When a client device wants to load a web page, what does it typically contact? A, a server, B, another client device, or C, a printer.

Pause the video whilst you have a think.

Did you select A, a server? Well done.

In order to navigate the World Wide Web, you need a web browser.

The most widely used web browsers are Google Chrome, Safari, Firefox, and Microsoft Edge.

To access a web page on the World Wide Web, you enter a website address into the address bar at the top of your browser.

This website address is known as the Uniform Resource Locator, or URL.

In this example, we've typed the URL https:///www.

raspberrypi.

org into our browser.

A website address is a user-friendly way of writing the address location of the server that stores the website.

A domain name system, DNS, helps match website names with where they're stored online.

When you type raspberrypi.

org into your browser, your device goes through a few checks to find the website.

Time to check your understanding.

I have a question for you.

What is the main function of a domain name system, DNS? Is it A, to match website names with their actual stored location, B, to store all of the web pages in the world, or C, to create new website addresses? Pause the video whilst you think carefully about your answer.

Did you select A? Great work.

The main function of a DNS is to match website names with their actual stored location.

First, your device checks if you've visited the site before.

If you have, your device may already know how to get there.

If not, it uses the DNS to look up where the website is located so your browser can open the web page.

The web browser connects to the web server where the website is stored using the location information provided by the DNS.

The web browser then makes a request for the web page.

The server will then check what has been requested and start to build a response.

Web pages are typically built using a markup language known as HTML.

The server will prepare the HTML required to build the web pages in your browser.

It will then send that HTML page and any other files, like images, to your computer.

The browser then takes the HTML and builds the web pages within your browser.

This is then displayed as a fully functioning web page.

Okay, we're moving on to our first task of today's lesson, Task A.

Getting online to view websites involves many different parts working together.

Name and explain one example of each of the following: A, hardware, a physical device that helps you access websites, B, software that helps you access websites, and C, transmission media, how data travels, that help you access websites.

Pause the video whilst you complete the task.

How did you get on with the tasks? I'm sure you did a great job.

Let's have a look at some sample answers together.

So part A was hardware, a physical device that helps you access websites.

A laptop or phone is a physical device used to send requests for websites and display what's on them.

Part B was software that helps you access websites.

A web browser, like Chrome, is the programme used to type in addresses and show website content.

Part C was transmission media that helps you access websites.

Wi-Fi, or cables, is the way data travels wirelessly through the air from your router to your device to bring you to the website.

Remember, if you want to pause the video here to add any detail to your answers, you can do that now.

For part 2, I'd like you to explain how both hardware and software, including the DNS, work together to allow you to access and display web pages.

Pause the video whilst you have a go at the task.

How did you get on? Let's have a look at a sample answer together.

To access a web page, your hardware, like a phone or laptop, and software work together.

You type a website address, or URL, into a web browser, which is software on your device.

The browser then uses the domain name system, DNS, to find the website's location on a server.

Once found, the browser receives the web page information and displays it on your device's screen.

Okay, so we've described how hardware and software support the World Wide Web.

Let's now move on to explain how data is transmitted using data packets.

Aisha says, "Now I get how devices and software work together to get me online." Alex says, "Same here.

It's kind of cool knowing what's behind the scenes." Aisha says, "But there's one thing I'm still wondering.

When I load a website or send a message, how does that data actually travel across the internet?" Have you ever thought about that question? Maybe pause the video for a couple of moments and have a think.

Alex says, "There must be a system for moving it around." Aisha says, "I've heard people talk about packets, but I've no idea what that actually means." Alex says, "It's probably the next piece of the puzzle." Let's see if Alex is right and explore some more information about these data packets.

Data files are broken down into smaller sections of data called data packets.

A data packet is a small unit of data sent over a network.

Each data packet contains a destination address, a source address, a data packet number so that the packets can be reassembled in the correct order, error checking to detect if data has been changed or corrupted during transmission to allow it to be resent.

Time to check your understanding.

I have a question for you.

What is a data packet in the context of data sent over a network? Is it A, a large, entire file, B, a small unit of data, or C, a type of network cable? Pause the video whilst you think about your answer.

Did you select B, a small unit of data? Well done.

In packet switching, data is divided into smaller packets, which are transmitted individually across the network.

Routers examine the destination address of each incoming packet and decide which route the packet should be sent along until the destination is reached.

Different packets from the same file could be sent separately along the most efficient route.

At the destination, the packets are reassembled into the correct order.

Most traffic over the internet uses packet switching.

Alex has a question, "Why not just send the whole file at once? Why bother splitting it into data packets?" That's a really good question, Alex.

Maybe pause the video whilst you think about Alex's question.

Why are data packets used? Data packets can be sent separately and don't all need to travel the same route.

If one packet is lost or corrupted, only that packet needs to be sent again, not the whole file.

Packets can take the fastest path available through the internet.

Time to check your understanding.

I have a question for you.

In packet switching, what is the role of routers? Is it A, they examine destination addresses and decide the best route for each packet, B, they reassemble packets into the correct order, or C, they store all packets from a file until the entire file is received? Pause the video whilst you think about the answer.

Did you select A? Well done.

The role of routers is to examine destination addresses and decide the best route for each packet.

Okay, we're moving on to our second task of today's lesson, Task B, and you've done a fantastic job so far, so well done.

For part 1, explain how packet switching works when data is sent over a network.

For part 2, describe two key benefits of using data packets to send data over the internet.

Pause the video whilst you complete the tasks.

How did you get on with the task? I'm sure you did a fantastic job.

Let's have a look at some sample answers together.

For part 1, you were asked to explain how packet switching works when data is sent over a network.

In packet switching, large files are divided into smaller individual packets.

These packets are then sent separately across the network.

At the destination, they're put back together in the correct order.

You could think of it like a puzzle where we send the individual puzzle pieces separately and then put them all together at the other end.

For part 2, you were asked to describe two key benefits of using data packets to send data over the internet.

Data packets can be sent separately, so don't all need to travel the same route.

This allows them to take the fastest path available through the internet, which makes data transfer quicker.

If one packet is lost during its journey, only that specific packet needs to be sent again.

This means the whole file doesn't have to be resent, saving time and ensuring the data arrives correctly.

Remember, if you'd like to pause the video here to add any detail to your responses or to go back through and have a look through the previous slides, you can do that now.

Okay, we've come to the end of today's lesson, "How data travels across the internet." And you've done a fantastic job, so well done.

Let's summarise what we've learned in this lesson.

The domain name system, or DNS, is used to find the location of the server that hosts the website.

To transmit this data across the internet, the data is broken down into smaller units called data packets.

The internet uses a method called packet switching, which allows each packet to take the most efficient route through the network.

I hope you've enjoyed today's lesson, and I hope you'll join me again soon, bye.