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Terms of Use

Last updated: 25 June 2026

These Terms of Use (the “Terms”) govern your use of the Quark app for iOS (the “App”) and this website (the “Site”), provided by Finn Geertz (“we”, “us”). By downloading, installing, or using the App, you agree to these Terms. If you do not agree, please do not use the App.

1. License

We grant you a personal, limited, non-exclusive, non-transferable, revocable license to download and use the App on Apple devices that you own or control, solely for your personal, non-commercial learning purposes, in accordance with these Terms and the Apple Standard EULA, which also applies to your use of the App.

2. Acceptable use

You agree not to:

3. Educational content disclaimer

Quark is an educational tool intended to help you learn physics. While we strive for accuracy, the content is provided for general learning purposes and may contain simplifications or errors. It is not a substitute for professional, academic, or examination advice, and we make no guarantee that it is complete, current, or error-free.

4. Intellectual property

The App, the Site, the “Quark” name and logo, the user interface, illustrations, text, and code are owned by us or our licensors and are protected by copyright and other laws. Some media displayed in the App (for example photos in the Feed) is provided by third parties under their own licenses (e.g. Creative Commons); the respective authors and licenses are credited where required. Except for the license in Section 1, no rights are granted to you.

5. Third-party services

The App may load content from third-party sources (such as Wikimedia Commons) and is distributed via Apple’s App Store. Your use of those services is subject to their own terms and policies, over which we have no control. See our Privacy Policy for details on data handling.

6. Purchases

The App is currently offered free of charge. If paid features or in-app purchases are introduced in the future, they will be processed by Apple under its terms, and any applicable pricing and refund rules will be presented to you before purchase.

7. Disclaimer of warranties

To the maximum extent permitted by law, the App and Site are provided “as is” and “as available” without warranties of any kind, whether express or implied, including fitness for a particular purpose and non-infringement. We do not warrant that the App will be uninterrupted, secure, or error-free. Mandatory statutory warranty rights for consumers remain unaffected.

8. Limitation of liability

To the extent permitted by law, we are liable without limitation only for damages caused intentionally or by gross negligence, and for injury to life, body, or health. For slight negligence, we are liable only for breach of an essential contractual obligation (cardinal obligation), and only up to the foreseeable, typical damage. Any further liability is excluded. Liability under the German Product Liability Act remains unaffected.

9. Changes to the App and Terms

We may update, modify, or discontinue the App or parts of it at any time. We may also amend these Terms; the current version is always available on this page. Continued use of the App after changes take effect constitutes acceptance of the updated Terms.

10. Term and termination

These Terms apply for as long as you use the App. You may end them at any time by uninstalling the App. We may suspend or terminate your license if you materially breach these Terms.

11. Governing law

These Terms are governed by the laws of the Federal Republic of Germany, excluding its conflict-of-law rules and the UN Convention on Contracts for the International Sale of Goods (CISG). If you are a consumer, this choice of law does not deprive you of the protection of mandatory provisions of the law of your country of residence.

12. Contact

Questions about these Terms? Email finngeertz@gmail.com. See also our Impressum.