Explain HTTP and HTTPS
Describe how web protocols carry requests and responses and why HTTPS protects data in transit.
Section 5 · The internet and its uses
This sequence follows Cambridge IGCSE Computer Science 0478, 2026–2028 syllabus Version 6. It covers subject content sections 5.1–5.3 only. The separately published 2029–2031 syllabus is not mapped here. Practice is original, self-checked and does not award an official Cambridge grade. Full timed papers and human subject-teacher review remain outstanding.
Before you begin
- No programming language is required. Be comfortable with place value and multiplication; each lesson introduces the computer-science notation it uses.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What does HTTP govern?
What you will learn
- Explain HTTP's role in web communication
- Describe request and response
- Explain HTTPS encryption and its limits
Protocols set communication rules
Hypertext Transfer Protocol (HTTP) defines how a browser and web server exchange web requests and responses. The browser requests a resource; the server returns a response that can include page data such as HTML.
Apply and check the rule
HTTPS uses HTTP over a protected connection. It encrypts data while it travels and helps the browser check the server's identity. Encryption protects the connection, but it does not prove that a website's content is honest or safe. Modern HTTPS generally uses TLS, the successor to the SSL wording found in some older specifications.
Pause and explain
A page uses HTTPS but imitates a bank. What is true?
Worked example
A student submits a password through a web form. Why should the site use HTTPS?
Show the worked solution
- The password travels between browser and server.
- HTTPS encrypts data in transit and helps authenticate the server.
- It does not make a fake or dishonest site trustworthy by itself.
Answer HTTPS helps protect the password while it travels, but the student must still check that the site is the intended service.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Describe what happens when a browser requests a page using HTTP.
Give me a hint
Include both parties and the response.
Compare my reasoning
- The browser sends an HTTP request for a resource.
- The server processes the request.
- The server returns an HTTP response, such as page data.
The browser requests the resource from the web server; the server responds with the requested data or an error response.
Look for these in your work
- Request sender
- Server role
- Response included
Give one reason HTTPS is safer than plain HTTP when signing in, and one limit to that protection.
Give me a hint
Separate connection security from website trust.
Compare my reasoning
- HTTPS encrypts information while it travels.
- It helps the browser establish the server identity.
- A deceptive site can still use HTTPS, so the URL and site must be checked.
HTTPS reduces the risk of someone reading the password in transit, but it does not prove the site belongs to the organisation it claims to represent.
Look for these in your work
- Encryption benefit
- Authentication role
- Limit stated
A café's sign-in page has HTTPS. A student says, “The padlock proves this page is safe.” Correct the conclusion.
Give me a hint
State exactly what the protected connection can establish.
Compare my reasoning
- HTTPS indicates a protected browser-server connection.
- It does not certify every claim or download offered by the website.
- The student should inspect the domain and use trusted links before entering information.
The padlock indicates connection protection, not a guarantee that the site is genuine or harmless. Check the domain and context before sharing information.
Look for these in your work
- What HTTPS means
- What it cannot guarantee
- Practical next check
Common mistakes
- Saying HTTPS guarantees a website is legitimate
- Saying HTTP and HTTPS are unrelated protocols
What can you explain now?
What protection does HTTPS add to web communication?
Compare with the explanation
It protects the connection, including encryption in transit
The browser and server use a secure version of HTTP; content trust still needs separate judgement.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
What does HTTPS add, and what does it not guarantee?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.