Free Software

Free software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions only to ensure that further recipients can also do these things. To make these acts possible, the human readable form of the program (called the source code) must be made available and the software must be accompanied by a software licence saying that the copyright holder permits these acts (a free software licence). Software can also be free software by putting the source code in the public domain.
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The free software community is an informal term referring to the users and developers of free software as well as supporters of the free software movement. The free software community is also called the "open-source community" and the "Linux community".The free software community includes individuals, groups, and companies who use free software because they believe that the freedoms to help yourself and to collaborate with others should be fundamental human rights, and it includes those who see free software as a way to make money.
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According to Richard Stallman and the Free Software Foundation, free software is software that everyone is free to copy, redistribute and modify. That implies it must be available as source code. It does not imply that it is free of charge, so anyone can sell free software so long as they don't impose any new restrictions on its redistribution or use.
This dictionary is free in this sense, though it is not really software.
There are many other kinds of "free software" in the more obvious sense of "free of charge". See "-ware".