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The OSGeo is not a primary source of information regarding Free Software or Open Source. Please refer to the corresponding web sites for a thorough treatment. This page intends to give a quick insight to the topic and explain some basics. Feel free to edit this page if you feel that it is not enough or needs pruning.
Free Software is a legal construct to protect source code from being commercially exploited by proprietary business models. This construct is know as Copyleft which is not the contrary of Copyright but uses Copyright to protect information from becoming proprietary. At the same time a healthy Business ecology is growing around Free Software offering Commercial Services of all kinds.
Free Software is closely related (and in many contexts perceived as identical) to Open Source.
The Free Software definition allows for several freedoms that enable individuals to collaborate easily on a project. As the source code is protected from becoming proprietary it is not necessary to de-sign and then-sign complicated contracts that define who may use the software for which purpose.
Commercial Use of Free Software
Free Software is not anti-commercial! There are many companies and individuals who make a living by producing, maintaining and enhancing Free Software or by offering all kinds of Commercial Services around it. In the geospatial realm it has grown into a healthy Business ecology. Find a company near you that speaks your language using the Service Provider Directory. Add yourself if you provide services.