What best describes open-source libraries?

Open-source libraries are characterized by being developed and maintained by a community that allows users to access the source code, enabling them to use, modify, and distribute the software freely. This model fosters collaboration and innovation, as developers can contribute improvements or adaptations to the codebase. The fundamental principle of open-source software is that it promotes transparency and shared knowledge, allowing a more extensive user base to benefit from and refine the code within the framework of specific licenses that govern its use.

In contrast, options that describe software available for purchase, protected under copyright without rights to edit, or private software for individual use do not capture the essence of open-source libraries. These other descriptions imply restrictions on access, modification, or distribution, which are contrary to the principles of open-source licensing. This is why the choice highlighting the community aspect and the rights granted to users makes it the correct representation of open-source libraries.