Open source is a huge part of Facebook engineering. Whether we're building new data infrastructure tools like Corona and Presto to manage our warehouses on Hadoop, releasing a new mobile build tool like Buck, or improving PHP runtime with HHVM, open source projects are integral to our operations.  
We also believe that contributing to open source projects is one of the best ways a student can prepare for a job in the industry. Software development as a profession has many features that are distinct from computer science as an academic subject. Projects are often larger than the people who participate in them; project management and interpersonal relationships can have as much impact on software design as technical issues; and systems are ultimately evaluated by user satisfaction rather than technical merit. More...