🔒 Pro · Component 1 · 1.2.2 Applications Generation
1.2.2b Open Source and Proprietary Software
OCR H446 · A Level Computer Science · ~10 min read
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Open Source Software
Open source software is software whose source code is publicly available. Anyone can view, modify, and redistribute the source code, subject to the terms of its open source licence.
Key characteristics:
Source code is freely available to view and download.
Users can modify the source code to suit their needs.
Users can redistribute modified or unmodified versions, subject to licence terms.
Often developed and maintained by a community of volunteer contributors.
Typically available at no cost (though this is not a strict requirement of the definition — some open source software is sold).
Examples of open source software:
Linux (operating system kernel)
Firefox (web browser)
LibreOffice (office suite)
Python, Java (programming languages/runtimes)
Android (mobile OS, based on Linux)
VLC media player
WordPress (content management system)
Open source licences:
Even open source software has licences. Key licences include:
GPL (General Public Licence): "copyleft" — any derivative works must also be released as open source under the GPL. (Used by Linux.)
MIT licence: very permissive — allows use in proprietary software; no requirement to open-source derivatives.
Apache 2.0: permissive, but requires preservation of copyright and licence notices.
Proprietary (Closed Source) Software
Proprietary software is software where the source code is NOT publicly available. The copyright holder retains exclusive rights. Users obtain a licence to use the software, but cannot view, modify, or redistribute the source code.
Key characteristics:
Source code is kept secret (hence "closed source").
Users cannot modify the software.
Redistribution is controlled — copying/sharing is typically restricted.
Use is governed by an End User Licence Agreement (EULA).
Developed and supported by a commercial company.
Examples:
Microsoft Windows, Microsoft Office
Adobe Photoshop, Premiere Pro
iOS (Apple)
macOS
Most commercial video games
Comparison Table
Factor
Open Source
Proprietary
Source code access
Publicly available — can view and study
Not available — kept secret
Cost
Usually free to use
Usually requires purchase or subscription
Modification
Allowed (subject to licence)
Not allowed
Redistribution
Allowed (subject to licence)
Strictly controlled
Support
Community-driven; no guaranteed support
Formal support from developer (within support contract)
Security
More eyes on code can find vulnerabilities quickly; but vulnerabilities are also visible to attackers
Vulnerabilities hidden from attackers; but fewer eyes to find them
Development pace
Dependent on community contributions; can be fast but inconsistent
Structured development; managed release schedule
Reliability
Varies widely; major projects (Linux) are highly reliable
Generally reliable; backed by company QA
Customisation
Full customisation possible
Users limited to settings/options provided
Advantages and Disadvantages for Organisations
Open source — advantages for an organisation:
No licensing costs — saves significant budget, especially for large deployments.
Full access to source code — can audit for security vulnerabilities and customise for specific needs.
No vendor lock-in — not dependent on one supplier.
Large community support — many online resources, forums, documentation.
Peer-reviewed code — many contributors audit the code for bugs and security issues.
Open source — disadvantages for an organisation:
No guaranteed professional support — if something breaks, the company may struggle to get timely help.
May require technical expertise to install, configure, and maintain.
Updates may be less frequent or predictable than proprietary software.
Interface/usability may be less polished than commercial equivalents.
Compatibility issues with proprietary formats (e.g. LibreOffice vs Microsoft Office).
Proprietary — advantages for an organisation:
Professional technical support included (often with SLAs).
Regular, tested, managed updates.
Often more polished UI and better integration with other commercial tools.
Legal accountability — the vendor is responsible for the software functioning as described.
Proprietary — disadvantages for an organisation:
Licensing costs — can be substantial, especially for enterprise software.
Vendor lock-in — dependent on one company's roadmap and pricing decisions.
Cannot customise the software to specific needs.
Cannot audit the source code for security vulnerabilities.
Exam tip: For open source vs proprietary questions, the most frequent A Level evaluation point is security. Open source: more people can find bugs (good) but vulnerabilities are also visible to attackers (bad). Proprietary: vulnerabilities are hidden from attackers (good) but fewer people audit the code (bad). Make sure you argue both sides.
Exam tip: Remember the GPL "copyleft" — if you use GPL code in your software, you must release your code as GPL too. This is important for companies choosing open source components.
⚠ Common Mistakes
Saying open source means free to use commercially — the GPL restricts this. Always check the specific licence terms.
Saying open source is always more secure — it has more community eyes on the code, BUT vulnerabilities are visible to attackers too. This is a two-sided argument.
Confusing 'free software' (free as in freedom — the right to modify) with 'free software' (free as in cost). The terms are different: open source = freedom to modify; freeware = zero cost but may be proprietary.
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Worksheet — 1.2.2b Open Source and Proprietary Software
8 questions · 20 marks · instantly marked
Q1Define open source software and state two of its key characteristics.[3 marks]
✓ Mark scheme
Open source software is software whose source code is publicly available — anyone can view, modify, and redistribute it, subject to licence terms [1]; two from: source code is freely accessible [1]; users may modify the code to suit their needs [1]; users may redistribute modified or unmodified versions [1].
Q2Explain what is meant by proprietary software and give two examples.[3 marks]
✓ Mark scheme
Proprietary software is software where the source code is not publicly available; the copyright holder retains exclusive rights and users obtain a licence to use the software but cannot view, modify, or redistribute it [1]; two examples from: Microsoft Windows, Microsoft Office, Adobe Photoshop, iOS, macOS [1 each, max 2].
Q3Explain what the GPL (General Public Licence) requires and why this is important for companies that build commercial products using open source code.[3 marks]
✓ Mark scheme
The GPL is a "copyleft" licence that requires any software which incorporates GPL-licensed code to also be released under the GPL [1]; this means any derivative work must be open source [1]; this is important for companies building commercial products because if they use GPL-licensed components, they are legally required to make their own source code publicly available too, which may conflict with their business model of selling closed-source software [1].
Q4A school IT manager is choosing between open source (LibreOffice) and proprietary (Microsoft Office) for its computers. Give two advantages and one disadvantage of choosing the open source option.[3 marks]
✓ Mark scheme
Advantages (two from): no licensing costs, saving the school budget [1]; source code is available, enabling customisation or independent security auditing [1]; no vendor lock-in — not dependent on Microsoft's pricing decisions [1]; Disadvantage (one from): no guaranteed professional support — if something breaks, expert help may be harder to obtain quickly [1]; possible compatibility issues with Microsoft Office file formats used by parents/external organisations [1].
Q5Discuss the security implications of using open source software versus proprietary software. Consider both sides of the argument.[4 marks]
✓ Mark scheme
Open source — security advantage: code is publicly available so a large community can audit it; many eyes can spot and fix vulnerabilities quickly [1]; open source — security disadvantage: because the code is visible to all, vulnerabilities are also visible to malicious attackers before a fix is released [1]; proprietary — security advantage: source code is secret so attackers cannot directly see and exploit vulnerabilities in the code [1]; proprietary — security disadvantage: fewer people audit the code (only internal developers), so vulnerabilities may go unnoticed for longer [1].
Q6Explain what 'vendor lock-in' means and why it is a concern when choosing proprietary software.[2 marks]
✓ Mark scheme
Vendor lock-in is when an organisation becomes dependent on one supplier for a software product [1]; this is a concern because the vendor can raise prices, change terms, or discontinue support and the organisation has little choice but to comply or face costly migration to alternative software [1].
Q7Distinguish between 'open source' and 'freeware'. Can software be proprietary but free of charge?[2 marks]
✓ Mark scheme
Open source refers to access to the source code and rights to modify/redistribute; it is about freedom of use rather than cost [1]; freeware is software that is available at no cost but the source code is not necessarily available — it may still be proprietary (e.g. old versions of Skype, Adobe Acrobat Reader). Yes, software can be proprietary but free of charge [1].
Q8Give two advantages that proprietary software offers over open source software for a large business.[2 marks]
✓ Mark scheme
Any two: professional technical support with guaranteed response times/SLAs — important for business-critical systems [1]; regular, managed, tested updates with a predictable release schedule [1]; legal accountability — the vendor is liable if the software fails to meet its described specifications [1]; generally more polished UI with better integration with other enterprise tools [1].
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Mini Test — 1.2.2b Open Source & Proprietary
10 questions · 10 marks · 10 minutes
5 MCQ + 5 short answer
⏱10:00
10 marks
Section A — Multiple Choice
Q1Which of the following is NOT a characteristic of open source software?
Q2The GPL (General Public Licence) is described as 'copyleft' because:
Q3An organisation chooses open source software and benefits from being able to audit the source code for security issues. This is an advantage because:
Q4Which of the following is a disadvantage of proprietary software?
Q5Freeware is best described as:
Section B — Short Answer
Q6Give two examples of open source software.
Mark schemeAny two from: Linux, Firefox, LibreOffice, VLC, Android, Python, WordPress. [1 mark each, max 2 for 2 marks]
Q7What is vendor lock-in?
Mark schemeVendor lock-in is when an organisation becomes so dependent on one supplier's software that switching to another product is costly or difficult — giving the vendor leverage to raise prices or change terms. [1 mark]
Q8State one security disadvantage of open source software.
Mark schemeBecause the source code is publicly available, vulnerabilities in the code are also visible to malicious attackers, potentially allowing them to exploit security flaws before a patch is released. [1 mark]
Q9Why might a large company prefer proprietary software over open source for business-critical systems?
Mark schemeProprietary software typically comes with professional technical support and SLAs (service level agreements) — guaranteed response times if something breaks, which is critical for business-critical systems that cannot afford extended downtime. [1 mark]
Q10Give one advantage of open source software for an organisation concerned about licensing costs.
Mark schemeOpen source software is typically available at no cost, saving significant licensing expenditure, which is especially valuable for large deployments (e.g. a school or hospital with hundreds of machines). [1 mark]