A software licence is a legal agreement that sets out the rights a user has to use, copy, modify, and distribute a piece of software. The type of licence determines whether you must pay to use the software, whether you can view or change the source code, and what you can do with any modifications you make.
Why does software need a licence?
Software is protected by copyright law from the moment it is created. Without a licence, you have no legal right to use it at all — even if it is freely downloadable. A licence grants specific permissions while reserving others for the copyright holder.
Think of a licence like a rental agreement. Owning a copy of a book does not give you the right to photocopy and sell it — the publisher retains those rights. Similarly, buying software gives you the right to run it, but not necessarily to copy, modify, or redistribute it.
What is a proprietary (closed-source) licence?
A proprietary licence grants users the right to run the software but retains all other rights for the vendor. The source code is kept secret (closed source).
| Feature | Proprietary licence |
|---|---|
| Cost | Usually paid (purchase or subscription) |
| Source code | Not provided — users see only compiled executable |
| Modification | Not permitted |
| Redistribution | Not permitted without the vendor's authorisation |
| Examples | Microsoft Windows, Adobe Photoshop, macOS |
Proprietary vendors argue that keeping the source code secret protects their investment in development and prevents competitors from copying their work. The drawback for users is that they are dependent on the vendor for updates, fixes, and continued availability.
What is an open-source licence?
An open-source licence grants users the right to view, use, modify, and usually redistribute the source code, subject to conditions that vary by licence.
Common open-source licences:
GPL (General Public Licence) — Modifications must also be open-source
("copyleft" — openness is inherited)
MIT Licence — Almost no restrictions; can be used in
proprietary products
Apache Licence 2.0 — Similar to MIT; includes patent protection
BSD Licence — Very permissive; credit required
The key philosophical division is between copyleft licences (such as GPL), which require that any modified versions also remain open source, and permissive licences (such as MIT), which allow the code to be incorporated into proprietary products.
Linux, Android, Python, and Firefox are all built on open-source software.
What are freeware and shareware?
Freeware is software distributed free of charge, but with no access to the source code. Unlike open-source software, you cannot modify or redistribute freeware. The author retains full copyright.
Shareware is software distributed free for a limited trial period or with limited functionality, encouraging users to pay for the full version after trying it. It is a marketing strategy rather than a philosophical stance on openness.
| Type | Free to use? | Source code available? | Can be modified? | Examples |
|---|---|---|---|---|
| Proprietary | Usually paid | No | No | Microsoft Office, Photoshop |
| Freeware | Yes, indefinitely | No | No | VLC (earlier versions), IrfanView |
| Shareware | Free trial only | No | No | WinZip (historically) |
| Open source | Usually free | Yes | Yes (with conditions) | Linux, Firefox, Python |
Note: VLC is now open source (GPL); it is cited here for its historical freeware period. The distinction matters because freeware ≠ open source.
What are Creative Commons licences?
Creative Commons (CC) licences are used primarily for creative works — text, images, music — rather than software, but they are examined in computing because they determine what you can legally do with online content.
The key components of a CC licence are:
- BY (Attribution) — you must credit the original creator
- SA (ShareAlike) — your modified version must carry the same licence
- NC (NonCommercial) — you may not use it for commercial purposes
- ND (NoDerivatives) — you may not create modified versions
These are combined: CC BY-NC-SA means you can use and adapt the work non-commercially, provided you credit the creator and release your adaptation under the same terms.
CC0 (Public Domain Dedication) — the creator waives all rights; anyone may use the work for any purpose.
What is the difference between software licence and copyright?
Copyright is the automatic legal right that protects a creator's work from the moment it is made — you do not need to register it. A software licence is the mechanism by which the copyright holder grants others specific permissions to use the work. Copyright says "nobody can use this"; a licence says "you can use this, under these conditions".
Frequently asked questions
What is the difference between freeware and open-source software?
Freeware is free to use at no cost, but the source code is not provided and you may not modify or redistribute it. Open-source software provides the source code and grants the right to view, modify, and (usually) redistribute it. All open-source software is free to use, but not all free software is open source. Open source is about freedom (freedom to inspect and change the code), not just price.
What is a copyleft licence?
A copyleft licence (such as the GNU GPL) requires that any modified version of the software also be released under the same open-source licence. If a company uses GPL code in their product, the entire product's source code must also be made available under the GPL. This prevents companies from taking open-source code, making proprietary improvements, and selling a closed product — it ensures openness propagates forward.
Can you use open-source software in commercial products?
It depends on the licence. Permissive licences (MIT, Apache, BSD) allow open-source code to be incorporated into commercial, closed-source products without any obligation to publish your code. Copyleft licences (GPL) require that the whole product be released as open source if GPL code is included. Many businesses specifically choose MIT- or Apache-licensed libraries to avoid triggering GPL obligations.
What licence does Python use?
Python is released under the Python Software Foundation Licence (PSFL), a permissive open-source licence compatible with the GPL. This means Python can be used freely in commercial applications without requiring the application's source code to be published. The language itself is open source; software written in Python is owned by its author and can be licensed however that author chooses.
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