FOSS stands for Free and Open Source Software, which refers to software that is both free to use and whose source code is available for anyone to view, modify, and distribute. This model promotes collaboration and sharing, allowing developers to improve the software and adapt it to their needs. FOSS is often developed by communities of volunteers and organizations, making it accessible to a wide range of users. Popular examples of FOSS include the Linux operating system and the Apache web server. This approach fosters innovation and can lead to more secure and reliable software solutions.