Which term describes software where access to the source code is restricted to authorized users only?

• A. Closed Source Software (CSS)
• B. Open Source Software
• C. Shareware
• D. Public Domain Software

Answer: (A)

Access to the source code is restricted to authorized users. This describes closed source software, also known as proprietary software, where the source code is kept private and only the compiled executables are distributed. You typically need a license to use it, and you can’t view, modify, or redistribute the underlying code. By contrast, open source software makes the source code available to anyone under an open license, allowing inspection and modification. Shareware refers to trial software with limited use or features, not to how the source code is handled. Public domain software has no copyright restrictions, so its source, if provided, is freely usable and modifiable without licensing constraints. Therefore, the correct term is closed source software.