GCSE Computer Science
Understanding how computers communicate and share data across networks.
Learn about LANs, WANs, network topologies (star, bus, ring), and network hardware including routers, switches, and access points. Understand the TCP/IP protocol stack and how data packets travel across the internet.
This unit covers IP addressing, DNS, the difference between wired and wireless networks, and common networking protocols.
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AI-Generated Content - Not Yet Reviewed
This lesson content has been partially generated using AI and has not yet been reviewed by a human educator. It likely contains numerous issues, inaccuracies, and pedagogical problems. Do not use this content for actual lesson planning or teaching at this time.
How does a message you type in London reach someone in Tokyo in less than a second?
Start with a live demonstration: send a message to a friend/colleague in another country and time how fast they respond. Ask: 'How did those words travel thousands of miles almost instantly?' Show a world map with undersea cables. Reveal: every day, over 500 billion emails are sent. How is this even possible?
Resources:
https://www.submarinecablemap.com/ - interactive map showing global Internet infrastructure
Teacher Notes:
If possible, arrange this in advance with a contact abroad. The 'wow' factor of real-time global communication sets up the entire unit.
Build from their experience: 'Who has Wi-Fi at home? What devices use it?' List reasons why we connect computers: share files, share printers, share Internet, communicate, play games together. Define a network as 2+ computers connected to share resources. Discuss how life would be different without networks (carry USB everywhere, no streaming, no social media).
Teacher Notes:
Make it personal. Get students to count how many networked devices they interact with daily. Most will underestimate dramatically.
Introduce the two main types. LAN = Local Area Network (your school, your home, an office - small geographical area, usually owned by one organisation). WAN = Wide Area Network (covers large geographical areas, often made of connected LANs, like the Internet itself). Activity: Sort examples into LAN or WAN (school network, the Internet, home Wi-Fi, a bank's national network, a coffee shop's Wi-Fi).
Resources:
Printable cards with 10 network scenarios for students to categorise
Teacher Notes:
The coffee shop one is deliberately tricky - it's a LAN but connects to a WAN. Use this to discuss how networks connect to each other.
Discussion prompt: 'Why is your home Internet sometimes slow?' Collect ideas, then formalise: (1) Number of devices - more users = shared bandwidth = slower for each, (2) Bandwidth - the 'width of the pipe' (measured in Mbps), more bandwidth = more data can flow. Use the motorway analogy: bandwidth = number of lanes, data = cars. Traffic jam = network congestion.
Resources:
Visual showing data packets flowing through pipes of different widths
Teacher Notes:
Students often confuse bandwidth with speed. Clarify: bandwidth is capacity, not speed. A lorry carries more than a car, but doesn't necessarily go faster.
Introduce two models for organising networks. Client-Server: one powerful computer (server) provides services, others (clients) request them. Like a restaurant - kitchen serves, customers request. Examples: school network, Netflix, most websites. Peer-to-Peer: all computers are equal, share directly with each other. Like a potluck dinner - everyone brings and takes. Examples: BitTorrent, some multiplayer games. Discuss advantages/disadvantages of each.
Teacher Notes:
Be careful with BitTorrent - acknowledge it's used for piracy but also has legitimate uses (Linux distributions, game updates). Focus on the technical model, not the ethics (save that for later lessons).
Quiz scenario: 'A school has 30 computers in a building. Teachers can access files from any computer. Students complain the network is slow at lunchtime when everyone watches YouTube. What type of network is this? (LAN) What model? (Client-server) Why is it slow at lunch? (Too many devices sharing limited bandwidth).' Students write answers, then discuss. Preview next lesson: 'But what actual equipment makes all this work?'
Resources:
3-question formative assessment on LAN/WAN, performance factors, network models
Teacher Notes:
The scenario question tests application, which is key for the exam. Circulate and note common misconceptions.
Brief story of ARPANET - how the Internet started as a US military project and evolved into the global network we use today. Show the first-ever network diagram from 1969 with just 4 computers.
Connection: Helps students understand why networks developed and why we have different types (LAN vs WAN evolved from different needs).
Further Reading:
Explore why gamers obsess over 'ping' and how network performance directly affects their experience. Show examples of how a 200ms delay ruins competitive gaming.
Connection: Makes 'network performance factors' tangible and relevant to students who play online games.
Further Reading:
Support:
Stretch:
https://www.submarinecablemap.com/ - visualises global Internet infrastructure
Cisco Annual Internet Report - statistics on global Internet traffic
There's a tiny piece of hardware in your phone that has a unique code - no other device in the world has the same one. What is it?
Reveal the answer to the hook: it's the NIC (Network Interface Card), which has a unique MAC address. Demonstrate: show students how to find their device's MAC address (phone settings or ipconfig/ifconfig). Point out: this is 'burned in' at the factory - permanent and unique. This leads us to: what other hardware makes networks work?
Resources:
Step-by-step instructions for Windows, Mac, iOS, Android
Teacher Notes:
This hook works because every student has this hardware in their pocket. The 'unique in the world' aspect is genuinely surprising.
Explain the NIC (Network Interface Card/Controller) in detail. Every device that connects to a network needs one. It converts data into signals that can travel over the network. Can be built-in (like in laptops/phones) or added (like a USB Wi-Fi adapter). The MAC address is its unique identifier - like a passport number for your device.
Resources:
Images of various NICs - PCIe cards, USB adapters, integrated chips
Teacher Notes:
If you have old network cards to pass around, this really helps students understand it's physical hardware.
Two crucial devices that often get confused. SWITCH: connects devices within ONE network (like a LAN). Uses MAC addresses to send data to the right device. Like a post room sorting mail within an office. ROUTER: connects DIFFERENT networks together. Uses IP addresses to find the best path. Like a postal sorting office deciding which van goes where. Activity: 'Is this a switch job or a router job?' scenarios.
Resources:
Visual showing a switch connecting computers in an office, with router connecting to Internet
Scenario cards for switch/router classification activity
Teacher Notes:
The switch-in-a-building, router-between-buildings analogy works well. Many home 'routers' are actually router+switch+WAP combined - mention this to avoid confusion.
WAPs (Wireless Access Points) allow wireless devices to join a wired network. They're the bridge between Wi-Fi devices and the ethernet cables in walls. Explain: your home router probably includes a WAP. In offices/schools, separate WAPs are placed around the building to give coverage. Discuss coverage vs. interference trade-offs.
Teacher Notes:
Students might not realise that Wi-Fi still ultimately connects to physical cables somewhere. The WAP is that connection point.
Three main types: (1) COPPER CABLES (e.g., Ethernet) - cheap, easy, but limited speed and distance, can suffer interference. (2) FIBRE OPTIC - uses light, very fast, long distance, no electrical interference, but expensive and fragile. (3) WIRELESS - convenient and mobile, but can be intercepted, affected by walls/interference, generally slower than wired. Compare with table showing speed, cost, security, and use cases.
Resources:
Printable comparison chart for student notes
Physical cable samples to pass around if available
Teacher Notes:
If possible, get actual cable samples. The contrast between thin fibre and chunky ethernet is striking.
Group activity: Design a network for a small business with: 1 office (8 computers), 1 warehouse (2 computers), need Internet access, some staff use laptops wirelessly. Groups sketch their design labelling: NICs, switches, router, WAPs, transmission media. Gallery walk to compare solutions. Discuss: Why might different designs work? What trade-offs did groups make?
Resources:
A3 sheet with scenario requirements and space for diagram
Optional: stickers with router, switch, WAP, computer icons
Teacher Notes:
Accept multiple valid solutions. The key is students can justify WHY they chose specific hardware. This is excellent exam preparation as scenario questions are common.
Rapid recall: Teacher describes a function, students hold up or write the component name. 'Connects different networks together' (Router). 'Has a unique MAC address' (NIC). 'Allows wireless devices to connect' (WAP). 'Connects devices within one network using MAC addresses' (Switch). Preview next lesson: 'Now we know the building blocks, let's see how to arrange them...'
Teacher Notes:
This tests recall under time pressure, which helps consolidate learning. Note any components that trip students up.
Virtual tour of a Google or Microsoft data centre. Show the scale - millions of servers, specialised cooling, multiple redundant connections. This is where 'the cloud' actually lives.
Connection: Puts network hardware in context - these components exist at massive scale in data centres that power the services students use.
Further Reading:
How fibre optic cables work (total internal reflection, light pulses) and why they're replacing copper. Show how a single fibre can carry terabits of data. Discuss the current rollout of full-fibre broadband in the UK.
Connection: Extends understanding of transmission media beyond the basics, showing cutting-edge technology students may have at home.
Further Reading:
Support:
Stretch:
https://www.youtube.com/watch?v=XZmGGAbHqa0 - inside a real data centre
Code.org video breaking down Internet infrastructure
Prerequisites: 1
If one computer fails, will the whole network go down? The shape of your network determines the answer.
Tell the story (real or constructed) of a company whose network failed because one central device broke, versus another whose network kept working despite multiple failures. Ask: 'What was different about how these networks were designed?' Introduce the concept: the SHAPE (topology) of a network affects its reliability, cost, and performance.
Teacher Notes:
You could use the 2021 Facebook outage as a real example - a configuration change to their core routers took down Facebook, Instagram, and WhatsApp globally for 6 hours.
Draw a star topology: central switch/hub with all devices connecting directly to it. Like spokes on a wheel. Characteristics: easy to set up and expand, if one computer fails others keep working, BUT if the central device fails EVERYTHING fails, need lots of cable (one per device). Use classroom analogy: teacher (central device) communicating with each student (device) individually.
Resources:
Clear labelled diagram for student notes
Teacher Notes:
Most school/home networks use star topology. Point this out - students can relate to it.
Draw mesh topology: every device connected to multiple (or all) other devices. No single point of failure - if one connection breaks, data takes another route. BUT expensive (lots of cables), complex to set up and manage. Two types: full mesh (every device to every device) and partial mesh (some redundant connections but not all). Used in critical systems where reliability is paramount.
Resources:
Full and partial mesh examples
Teacher Notes:
Calculate together: in a full mesh with 5 devices, how many connections? (n×(n-1)/2 = 10). Scale up to show why full mesh becomes impractical at large scale.
Pair activity: Complete a comparison table for Star vs Mesh covering: Cost, Reliability, Ease of expansion, Maintenance difficulty, Single point of failure. Then apply: given 5 scenarios (home network, hospital monitoring system, small office, military communications, coffee shop), recommend star or mesh with justification.
Resources:
Table template and scenario questions
Teacher Notes:
The hospital and military scenarios should push towards mesh; home and coffee shop towards star. Discuss: why is cost acceptable in life-critical systems?
Revisit from Lesson 1 with more depth. Client-Server: central control, easier to secure and back up, server can become bottleneck, server failure affects everyone. Peer-to-Peer: no central control, harder to manage/secure, more resilient (no single point of failure), resources spread across all devices. Modern example: Spotify - client-server for library/accounts, but used to use P2P for actual music streaming to reduce server load.
Teacher Notes:
The Spotify example shows that real systems often blend models. This nuance is good for higher-ability students.
Discussion prompt: 'Should important systems like social media be controlled by central servers (owned by companies) or distributed peer-to-peer (owned by no one)?' Explore implications: Who controls your data? Who can censor content? What happens if the company goes bankrupt? Links to current debates about platform power.
Teacher Notes:
This addresses the social/ethical requirements. Accept diverse viewpoints - the goal is critical thinking, not a 'right answer'.
Scenario: A hospital needs to connect 3 buildings. Building A: admin offices (20 PCs). Building B: patient records server + 10 workstations. Building C: emergency department (5 critical monitoring systems). What topology would you use? What model (client-server or P2P)? Quick sketch and 2-sentence justification. Share and discuss.
Teacher Notes:
Look for: mesh elements for critical systems, star for general use, client-server for central records. Award credit for any well-justified design.
Brief introduction to how blockchain networks (like Bitcoin) use peer-to-peer architecture with no central server at all. Every participant has a copy of the entire ledger. Discuss why this matters for trust and security.
Connection: Takes the peer-to-peer concept to its logical extreme, showing how network architecture enables new technologies.
Further Reading:
How NASA uses a mesh-like network of ground stations to communicate with spacecraft across the solar system. Show how they maintain contact with Voyager (currently 24 billion km away!) using mesh redundancy.
Connection: Demonstrates mesh topology benefits at an extreme scale, showing why redundancy matters for critical systems.
Further Reading:
Support:
Stretch:
https://eyes.nasa.gov/dsn/dsn.html - real-time view of NASA's deep space network
Cloudflare blog explaining what happened technically
Prerequisites: 1, 2
When you type 'youtube.com', how does your computer know where YouTube actually lives?
Live demonstration: Open command prompt/terminal and run 'nslookup youtube.com'. Show the IP address that comes back. Explain: YouTube's real address is this number. Your computer doesn't know this - it has to look it up every time. This is DNS (Domain Name System). Like a phone book: you look up a name, you get a number.
Resources:
Commands for Windows/Mac/Linux to demonstrate DNS lookup
Teacher Notes:
This live demo is powerful because students can do it themselves. The 'magic' of URLs becomes understandable.
Key concept: The Internet isn't one network - it's millions of networks connected together. Your home LAN connects to your ISP's network, which connects to larger networks, which connect globally. Like roads: your street → local roads → motorways → international routes. No single organisation 'owns' the Internet, but many organisations manage pieces of it.
Resources:
Layered diagram showing home → ISP → backbone → content providers
Teacher Notes:
This is a critical conceptual shift. Students often think 'the Internet' is a single thing run by someone.
Deep dive into DNS: When you type a URL, your computer asks a DNS server 'What's the IP for this name?' DNS server responds with the IP address. Your computer then connects to that IP. Important: DNS is made up of many Domain Name Servers worldwide (not one central server). If one fails, others take over. Show simplified DNS lookup process diagram.
Resources:
Step-by-step visual of DNS resolution process
Teacher Notes:
Spec explicitly says 'DNS is made up of multiple Domain Name Servers' - make sure students understand this distributed nature.
Apply client-server model specifically to the web. Web Server: stores website files, responds to requests, 'serves' web pages. Web Client: your browser, requests pages, displays them for you. Hosting: companies that provide web servers for others to use (you don't need your own physical server). Examples of servers: web server (pages), file server (documents), email server (messages), game server (multiplayer).
Teacher Notes:
Students often think 'server' means a big expensive machine. Clarify it's about the ROLE (serving requests), not the hardware.
Demystify 'the cloud': It's remote computing - using computers somewhere else over the Internet. Three types of service: Storage (Google Drive, iCloud), Software (Google Docs, Office 365), Processing (rendering videos, running AI). Discuss advantages: access anywhere, no local storage limits, automatic backups, collaboration. Discuss disadvantages: need Internet, privacy concerns, ongoing costs, dependent on provider.
Resources:
Categorised list of cloud services students might use
Template for structured notes
Teacher Notes:
Make it concrete with services they use: Google Docs, iCloud Photos, Netflix. These are all 'cloud' services.
Split class into groups. Half argue FOR storing everything in the cloud, half argue AGAINST. Give 3 minutes to prepare, then structured debate: each side gives 2-minute opening, 1-minute response. Vote at the end. Debrief: What were the strongest arguments? When might cloud be better/worse?
Teacher Notes:
This addresses the 'advantages and disadvantages' specification point and builds evaluation skills needed for extended response questions.
Quick activity: Describe the journey when you search for a video on YouTube: (1) Type URL, (2) DNS lookup gets IP, (3) Browser (client) sends request, (4) YouTube's web server responds, (5) Video data (from cloud storage) streams to your device. Students sequence these steps, label client/server/DNS roles.
Teacher Notes:
This consolidates the whole lesson into one end-to-end example. Perfect recap activity.
Explore just how big DNS is - there are over 360 million registered domain names. Show how DNS is distributed across thousands of servers worldwide. Discuss what happens during a 'DNS attack' and how this can take down major services.
Connection: Deepens understanding of DNS as a distributed system, not just a single lookup.
Further Reading:
Reveal that 'the cloud' is just someone else's computer - usually in a massive data centre. Show map of major cloud provider data centres (AWS, Azure, Google). Discuss why data centre location matters (latency, legal jurisdiction, environmental impact).
Connection: Demystifies 'the cloud' and connects to concrete infrastructure students have learned about.
Further Reading:
Support:
Stretch:
https://howdns.works/ - illustrated comic explanation
AWS or Microsoft introductory videos
Prerequisites: 1, 2
Every device on the Internet has two addresses - one that never changes and one that changes all the time. Why would you need both?
Show students how to find their device's MAC address AND IP address. Point out: the MAC address is the same every time (permanent), the IP address might be different (can change). Ask: 'Why would we need both?' Accept hypotheses, then explain: MAC identifies the hardware (like a VIN on a car), IP identifies the location on the network (like a parking space number).
Resources:
Step-by-step for Windows (ipconfig /all) and Mac (System Preferences)
Teacher Notes:
Students love discovering things about their own devices. This hook works because it's personal and immediate.
Compare three connection types: ETHERNET (wired): Fast, reliable, secure, but need cables, not mobile. WI-FI (wireless): Convenient, mobile, but can be slower, affected by walls/interference, less secure. BLUETOOTH (wireless): Low power, short range, good for peripherals (headphones, keyboards), not for Internet. Build comparison table. Discuss: 'When would you recommend each?' Scenarios: gaming tournament, coffee shop, wireless earbuds, office desktop, security camera.
Resources:
Table template with criteria: speed, range, security, mobility, power use
Teacher Notes:
Most students intuitively know some of this but may not be able to articulate WHY. The scenarios help solidify understanding.
IP addresses identify devices on a network - like a postal address. IPv4 format: four numbers 0-255 separated by dots (e.g., 192.168.1.1). Explain: each number is 8 bits (1 byte), so 4 × 8 = 32 bits total. Problem: only ~4.3 billion combinations (we've run out!). IPv6 format: eight groups of 4 hex digits (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). 128 bits = virtually unlimited addresses.
Resources:
Visual showing format breakdown with bit counts
Teacher Notes:
Focus on PURPOSE and FORMAT - the spec explicitly says students don't need to know about static/dynamic or public/private distinctions.
MAC (Media Access Control) address is burned into every NIC - unique worldwide. Format: six pairs of hex digits (e.g., 00:1A:2B:3C:4D:5E). First three pairs identify the manufacturer, last three are the unique device ID. Used by switches to send data to the right device within a local network. Analogy: IP is like your street address (can change if you move), MAC is like your fingerprint (always the same).
Teacher Notes:
The 'fingerprint' analogy is strong. Note: MAC addresses CAN be spoofed by software, but this is beyond spec.
Imagine if every phone manufacturer used different charging cables... oh wait, they used to! Standards ensure different devices can work together. Example: USB standard means any USB device works in any USB port regardless of manufacturer. Network standards ensure: data is formatted the same way, signals work across devices, different manufacturers' equipment is compatible. Without standards, networks wouldn't work across different brands.
Teacher Notes:
The USB example is very relatable. EU forcing Apple to use USB-C is a current example of standardisation in action.
Why encryption matters: data on networks can be intercepted (especially wireless). Encryption scrambles data so only the intended recipient can read it. Simple demonstration: Caesar cipher - shift each letter. Real encryption is far more complex (but same principle). Show: HTTP vs HTTPS - the 'S' means encrypted (look for padlock in browser). Discuss: What should ALWAYS be encrypted? (Passwords, payments, personal info)
Resources:
Short message for students to encrypt/decrypt using letter shift
Teacher Notes:
Don't go deep into how encryption works mathematically - the spec just needs 'the principle of encryption to secure data'.
Give students several 'addresses' and ask them to identify if each is: IPv4, IPv6, or MAC. Then: scenario questions - 'A company wants to track which devices are connecting to their network - which address type would they check?' 'A website needs to know where to send your requested page - which address do they use?' Quick exit ticket on encryption: 'Why is HTTPS better than HTTP for online banking?'
Resources:
Mix of IP and MAC addresses for classification
Teacher Notes:
This tests recognition and application - both important for the exam.
The Internet is literally running out of addresses! Explore how IPv4 only has ~4.3 billion addresses and we've used them all. Discuss how organisations are transitioning to IPv6 (340 undecillion addresses - enough for every grain of sand on Earth to have its own!).
Connection: Explains why we have two IP formats and makes a 'dry' topic feel relevant and urgent.
Further Reading:
Brief look at the history of encryption, from the Enigma machine in WWII to modern HTTPS. Show how Alan Turing's work on code-breaking laid foundations for modern computer science.
Connection: Connects encryption to history and shows it as an ongoing challenge, not just a technical feature.
Further Reading:
Support:
Stretch:
https://ipv4.potaroo.net/ - real-time statistics
Khan Academy introduction to cryptography
Prerequisites: 1, 2
When you send an email, it doesn't go directly to your friend - it makes at least 3 stops using 3 different sets of rules. What are they?
Walk through what happens when you send an email: (1) Your email app uses SMTP to send to your email server, (2) Your server uses SMTP to send to recipient's server, (3) Recipient's server stores it, (4) Recipient uses POP or IMAP to retrieve it. At each step, different RULES (protocols) govern what happens. Reveal: the whole Internet runs on these agreed rules.
Resources:
Visual flowchart showing SMTP → server → SMTP → server → POP/IMAP
Teacher Notes:
This concrete example immediately demonstrates why we need multiple protocols for one simple task.
Protocol = set of rules for communication. Human analogy: when you answer the phone, there's an unwritten protocol (say hello, identify yourself, take turns speaking, say goodbye). Without these rules, phone calls would be chaos. Same with computers - protocols define: how to start a connection, how data is formatted, how to handle errors, how to end communication.
Teacher Notes:
The phone call analogy works well. You could roleplay a 'phone call without protocols' - both speaking at once, no greeting, abrupt ending.
Cover each protocol the spec requires. Use a table format: Protocol | Purpose | Key Feature. TCP/IP: Foundation of Internet communication, breaks data into packets, ensures reliable delivery. HTTP: Web page requests and delivery, 'language' between browser and web server. HTTPS: Same as HTTP but encrypted, secure for passwords/payments. FTP: Transferring files between computers, upload/download files from servers. SMTP: Sending emails, pushes mail from sender to servers. POP: Downloading emails, downloads and (usually) deletes from server. IMAP: Accessing emails, syncs across devices without downloading.
Resources:
Printable table with all protocols, purposes, and features
Teacher Notes:
Students don't need to memorise exact technical details, but must know PURPOSE and KEY FEATURES. The table format is exam-friendly.
Scenario cards: Match the protocol to the situation. 'You're downloading photos from a server to update a website' (FTP). 'You're entering your password to log into a bank' (HTTPS). 'You want to read emails on both your phone and laptop' (IMAP). 'You want to send a newsletter to 1000 subscribers' (SMTP). Students work in pairs, then review together.
Resources:
12 scenarios for protocol identification
Teacher Notes:
Some scenarios could have multiple valid answers - use these for discussion. The key is justification.
Concept of layers: Breaking complex systems into manageable parts. Each layer handles one job, passes to next layer. Analogy: Sending a package - you (write letter), packaging (put in envelope), postal service (transport), delivery (hand to recipient). Each 'layer' doesn't need to know how other layers work. Benefits: Easier to build and test, can update one layer without breaking others, different manufacturers can build different layers. Briefly mention TCP/IP as example of layered model.
Resources:
Side-by-side comparison of postal layers and network layers
Teacher Notes:
Spec explicitly says 'refer to 4-layer TCP/IP model' but students don't need to know individual layer names/functions. Focus on WHY layers are beneficial.
Guided activity using browser developer tools (F12 → Network tab). Visit a website and watch the HTTP/HTTPS requests happen in real-time. Point out: status codes (200 = OK, 404 = not found), request types (GET = requesting data), HTTPS padlock. Optional: Use online tool to check a website's HTTP headers.
Resources:
Step-by-step instructions for Chrome/Firefox/Edge
Teacher Notes:
This makes abstract protocols visible and concrete. Even just seeing the requests appear is revelatory for most students.
Rapid questions: 'Which protocol would you use to send an email?' (SMTP) 'Why is HTTPS better for banking than HTTP?' (Encrypted) 'What's the main advantage of IMAP over POP?' (Syncs across devices) 'Why do we use layers in network design?' (Easier to build/maintain, allows independent development). Final reflection: 'Which protocol do you use most in your daily life?'
Teacher Notes:
This tests recall under time pressure. Note which protocols cause confusion for revision focus.
Brief history of competing network protocols before TCP/IP won. Mention Apple's AppleTalk, Novell's IPX/SPX. Explain how TCP/IP became the universal standard through ARPANET and early Internet adoption.
Connection: Shows protocols as human creations that went through competition and selection, not inevitable.
Further Reading:
Show how apps talk to each other using protocols. Brief demo of a simple API call (weather API, for example). Connect this to their future learning - when they learn to program, they'll use protocols to connect their code to services.
Connection: Extends protocols beyond networks to software communication, linking to programming they'll do in Component 2.
Further Reading:
Support:
Stretch:
Fun illustrated guide to 404, 500, etc.
YouTube animation showing email's journey through protocols
Prerequisites: 4, 5