The document provides an overview of open source licensing. It defines open source software as software with an open source license that gives users the rights to use, modify, and distribute the software as well as access its source code. Prominent open source programs and vendors are listed. The history and roles of the Open Source Initiative (OSI) and Open Source Definition (OSD) are described. Common open source licenses like the GPL, BSD, and Mozilla licenses are outlined and compared. The risks and benefits of open source software are briefly discussed.