Free, Libre and Open Source Software (FLOSS) is software released under a license that allows developers to: 1) access the software’s source code, 2) use the software for free, and 3) develop derived works based on software’s previous releases. FLOSS’s success can be attributed to the motivations of the individuals that are members of the open source community. However, FLOSS’s recent boom is also associated with the adoption of many business models, which rely on FLOSS, by modern companies. The aim of this post is to summarize the reasons that make individuals and companies to participate in the open source community and highlight the impact of FLOSS projects on computer science. To name some of the most popular FLOSS projects, consider: the Eclipse IDE, the Firefox browser, the Apache server, the Linux kernel, the Java, C/C++, Python programming languages, the MySQL, SQLite, PostgreSQL databases, the GNOME and KDE desktop environments, the Git version control system, the R-Project for statistical computing, the TeX system for publishing, etc.