Open source is a set of principles and practices on how to write software. Literally “open source” means the source code is available to the users. The Open Source Definition, which was created by Bruce Perens and Eric Raymond and is currently maintained by the Open Source Initiative, adds additional meaning to the term. One should not only get the source code but also have the right to use it. If the latter is denied the license is categorized as a shared source license.
http://en.wikipedia.org/wiki/Open_source
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Open source is a development method for software that harnesses the power of distributed peer review and transparency of process. The promise of open source is better quality, higher reliability, more flexibility, lower cost, and an end to predatory vendor lock-in.
The Open Source Initiative (OSI) is a non-profit corporation formed to educate about and advocate for the benefits of open source and to build bridges among different constituencies in the open-source community.
One of our most important activities is as a standards body, maintaining the Open Source Definition for the good of the community. The Open Source Initiative Approved License trademark and program creates a nexus of trust around which developers, users, corporations and governments can organize open-source cooperation.
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http://sourceforge.net/
http://www.opensource.org/
http://www.opensourcewindows.org/