The free and open source software movement has had phenomenal impact on the industry evolution. Alongside its important technological innovations, FOSS has sparked novel business models, intellectual property strategies, and software development paradigms. This article reflects on FOSS achievements and provides practical guidelines for leveraging its strengths and mitigating its risks. FOSS also changed the way we develop software. Many current engineering processes have evolved from the way open source is developed. This holds for iterative development and agile techniques as well as globally distributed software engineering