What is the defining characteristic of open-source software?

The defining characteristic of open-source software lies in its inclusion of the uncompiled source code, which allows users to modify, improve, and distribute the software as they see fit. This access to the source code fosters collaboration and innovation within a community of developers and users. It enables individuals or organizations to customize the software to meet their specific needs and even contribute back enhancements to the broader community. This fundamental principle of transparency and communal effort distinguishes open-source software from proprietary software, where the source code is generally kept hidden from users.

While open-source software can often be free of charge, it is not a requirement for all open-source licenses. Additionally, open-source software is specifically designed to be modifiable; therefore, the inability to modify it would contradict the very concept of "open source." Finally, the idea that open-source software is only available to licensed users is inaccurate since it is designed to be freely accessible to anyone interested in using or contributing to it.