GNU (GNU's Not Unix)
GNU is a free and open-source operating system project initiated by Richard Stallman in 1983 as part of the Free Software Foundation (FSF). The acronym stands for "GNU's Not Unix," emphasizing its Unix-like structure while being entirely free of proprietary Unix code. The GNU Project laid the foundation for the Free Software movement, advocating for users' rights to run, study, modify, and distribute software freely.

Core Principles:
- Freedom: All software under GNU must comply with the FSF’s Four Freedoms, ensuring unrestricted use and collaboration.
- Open Collaboration: Promotes a community-driven approach to software development.

Key Components:
- GNU Utilities: Includes tools like bash, gcc, and grep, vital for system functionality.
- GNU/Linux: Often referred to simply as Linux, many distributions combine GNU software with the Linux kernel to form a complete operating system.
- Licensing: The GNU General Public License (GPL) ensures software freedom and encourages sharing modifications.

Impact:
- Software Development: Inspired the creation of other free and open-source projects, such as Apache and Mozilla.
- Cultural Shift: Sparked debates on software ownership and ethics, influencing modern open-source practices.

GNU represents a philosophical and practical commitment to software freedom, continuing to influence the technology industry and digital rights advocacy.