Any time you withdraw cash from an ATM, call someone on a cell phone, or watch a movie during a flight, chances are you have Linus Torvalds to thank. His Linux operating system powers the web servers of some of the world’s best-known technology companies as well as billions of Android mobile phones. Torvalds started working on Linux in 1991 while studying for a master’s degree in computer science at the University of Helsinki, but instead of focusing on making a profit, he shared his code with other programmers so they could contribute to it and make improvements. That approach made him one of the godfathers of open-source software, in which the original code is made available for free and can be modified and redistributed. Torvalds moved to California with his family in 1997 to join the semiconductor start-up Transmeta but left the company a few years later to focus exclusively on developing Linux through nonprofit ventures, which merged in 2007 to become the Linux Foundation, where he is a fellow. In 2005 Torvalds created Git, another open-source tool, which facilitates collaboration among software developers. Git is now the most widely used distributed system for maintaining version control in the world, relied on by commercial and open-source developers alike. His pioneering contributions have earned Torvalds numerous accolades. He shared the 2012 Millennium Technology Prize and was voted one of the “most important people” of the 20th century in a 1999 Time poll. The Linux Foundation has opposed immigration restrictions as “antithetical to the values of openness and community that have enabled open source to succeed.”