Denoting software that is freely available with its source code, to be used or altered by anybody as they wish. Commonly the only restriction is that it cannot be charged for, that its free distribution should not be hindered, and that the work of others should be properly respected. Behind such software lies a belief that the cooperative approach it seeks to foster is the best way to create high quality software, through widespread inspection, modification, and correction of the source code by any interested party. It is contrasted especially with the traditional proprietary model, where source code is a closely guarded commercial secret. A strong recent trend has been the emergence of websites that use software version control tools to provide online source code hosting (e.g. GitHub, SourceForge).