Free and Open Source Software (FOSS) refers to software that is both free to use and whose source code is openly available for anyone to view, modify, and distribute. This means users can not only run the software but also adapt it to their needs, fostering innovation and collaboration within the community. Examples of FOSS include Linux, Mozilla Firefox, and LibreOffice. The principles of FOSS promote transparency and user freedom, allowing individuals and organizations to avoid vendor lock-in and proprietary restrictions. By encouraging contributions from a diverse range of developers, FOSS projects often benefit from rapid improvements and a wide variety of features, making them popular choices for many users and businesses.