Not all Open Source licenses are the same. Some of them obligate the software supplier to grant patent licenses to users and developers of the software. Other licenses oblige the developer that uses the licensed product or library to offer the source code of this product or library under the same terms. Others simply give away the code, with no warranty of any kind or any concerns.
This article highlights the main differences between the most used Open Source licenses from the perspective of a software user and of a software developer. First we need to speak about the specific properties that define Open Source software.
All Open Source software, according to the Open Source Initiative, is distributed under a license that gives its users and developers (the licensees) some rights. The full list can be consulted in the Open Source Definition
The question is, can we use an Open Source software in the development of a product or project? Basically, it depends on the license of the used software and the intended license for the final product. The different licenses also matter when you want to publish your own code as Open Source and you are deciding which license you should use.
One pretty interesting concept about Open Source licenses is what is usually called copyleft, the opposite of copyright. Where copyright is used to protect intellectual property (including software) from being copied or distributed, copyleft is used to ensure that open-sourced intellectual property and software can be copied or distributed as open source. According to its strength, there are two kinds of copyleft:
-Strong copyleft: when works derived from other strong-copyleft licensed works, or linked to these works, must continue having strong copyleft licenses, or even exactly the same license. That is, those Open Source works cannot be closed in the future.
-Weak copyleft: when works using weak copyleft licensed works, or linked to it, can be licensed under other licenses, even closed-source licenses. In this case, the copyleft only affects the original weak copyleft licensed work.
There are also Open Source licenses without copyleft: they simply don’t care about future openness of derived software.
To learn more about Open Source licenses, read the full article here