Over the last 20 years, a phenomenon has evolved in the software industry that is now emerging as a fundamental shift in how software is developed and distributed: open source software. Open source software touches the very heart of the software industry - how software companies can make money. The open source software movement has significantly upped the ante for commercial players. Companies now must compete based on their business models, in addition to other traditional forms of competition. Today, the software industry is characterized by an ever-changing mix of excitement, caution, hype, confusion, experimentation, failure, and success - thanks in no small part to open source software. As the open source movement expands up the software stack, nearly all software markets are now being impacted in some way.