Certified Information Systems Security Professional (CISSP) Practice Exam

Closed source software is defined by the confidentiality of its source code, meaning that the code is not made available to the public. This approach restricts users from viewing, modifying, or distributing the source code, which is a characteristic that distinguishes it from open source software where the source code is freely available for users to inspect and alter.

Companies often utilize closed source software to protect their intellectual property and maintain control over their products. This control can also serve to ensure stability and security, as the company can manage updates and patches in a structured manner. By keeping the source code confidential, developers can protect proprietary algorithms and trade secrets that give their software a competitive edge.

The other choices depict characteristics of software that either promotes openness (such as open source licenses) or refers to access models (like subscription-based access), which do not define the core essence of closed source software. Therefore, the understanding of closed source hinges on the proprietary nature of the code and the limitations placed on users regarding modifications and distribution.