"Free and Open Source" (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 that users can not only run the software but also adapt it to their needs, fostering innovation and collaboration within the community. FOSS promotes transparency and user control, as anyone can inspect the code for security vulnerabilities or bugs. Popular examples of FOSS include the Linux operating system and the Apache web server, which are widely used and supported by a global community of developers and users.