The Mozilla Public License (MPL) is a permissive open-source license that allows developers to use, modify, and distribute software while imposing certain restrictions to ensure that the source code remains accessible. One of the primary restrictions of the MPL is that if you modify MPL-licensed code and distribute it, you must also make the source code for your modifications available under the same license. This means that any changes you make to the original code must be shared openly with the community, promoting collaboration and transparency.
Another important aspect of the MPL is that it incorporates a file-level copyleft requirement. This means that while you can combine MPL-licensed code with other proprietary code, any modifications to the MPL-licensed files themselves must remain under the MPL. For example, if you have a project that includes an MPL-licensed library and you alter some of its files, those altered files must still be shared as MPL. However, you can keep your proprietary code separate, which allows some flexibility in how you use the software while still adhering to the license's stipulations.
Lastly, developers should also consider that the MPL requires proper attribution. When distributing MPL-licensed software, you must retain notices of copyright and license information, ensuring that original authors and contributors are credited. This is an essential part of the license, as it acknowledges the work of those who created the software. Overall, while the MPL offers freedoms similar to other open-source licenses, its specific requirements regarding modification, source code availability, and attribution are key for developers to understand when working with MPL-licensed projects.