What does the term 'closed-source' imply in software licensing?

The term 'closed-source' in software licensing indicates that the source code of the software is not made available to the public. As a result, users cannot access, modify, or distribute the source code freely. This restriction means that the licensee—typically the user or organization that holds a license for the software—has limited rights when it comes to altering the software. The intent of closed-source licensing is to protect the intellectual property of the developers and maintain control over how the software operates and is distributed.

The other options suggest scenarios that involve open access or modification rights, which are not characteristic of closed-source software. For instance, being free to modify and distribute or available for public modification directly contradicts the essence of closed-source licensing. Similarly, being available under general public licensing implies a level of openness and freedom that is incompatible with closed-source principles.