Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code,design documents, or content of the product. The open source model is a decentralized software development model that encourages open collaboration. A main principle of open source software development is peer production, with products such as source code, blueprints, and documentation freely available to the public. The open source movement in software began as a response to the limitations of proprietary code. The model is used for projects such as in open source appropriate technology, and open source drug discovery.
Some good jumping off points from this are open source game engine recreations that allow people to do things like play Doom on their phones and the various licenses that open source projects use like GPL, BSD, MIT, and ‘Do What The Fuck You Want To Public License’ and the differences between them and how companies have dealt with their restrictions
In regards to that last point here is an article about rsync and Apple
