Open Source
Here, we are quoting the definition of the Open Source Initiative. The founder of Free Software and manager of the most-used GPL license is the Free Software Foundation.
The definition of Open Source software, Version 1.9
Introduction
"Open Source" means more than just free access to the source code. In the case of Open Source software, the licensing conditions must correspond the following criteria in regard to the distribution of the software:
1. Free distribution
The license may not limit anyone in his or her right to distribute or sell the software as part of a software package that contains program of various origin. In case of such a sale, the license may not prescribe licensing or other fees.
2. Source code
The program must contain the source code. The distribution must be permitted both for the source code and the compiled form. If the program is distributed in another form without source code, there must be a generally known possibility to obtain the source code at cost, preferably as a fee-free download from the Internet. The source code should be in the form of a program that a programmer has preferably processed. Source code intentionally written in an incomprehensible manner is thus not permitted. Intermediate forms of the code, such as that generated by a preprocessor or converter (translator) are impermissible.
3. Derived software
The license must permit changes and derivatives. In addition, it must permit that programs arising in this manner under the same licensing conditions can be further distributed in the same way as the original software.
4. Intactness of the source code of the author
The license may limit the possibility to distribute the source code in changed form only if it provides that so-called patch files may be passed on with the source code that change the program code during compilation. The license must expressly permit the distribution of software arising from changed source code. The license can demand that the derived programs have another name or another version number than the original software.
5. No discrimination of people or groups
The license may not discriminate against anyone.
6. No limitations in regard to the area of application
The license may not prevent anyone from using the program in a certain area. For example, it may not exclude the use of the program in a business or in genetic research.
7. Distribution of the license
The rights to a program must transfer to everyone who obtains this software without the necessity of obtaining an own, additional license arises.
8. The license may not be limited to a certain product package.
The rights to a program may not depend on whether the program is part of a certain software package. If the program is removed from the package and used or distributed within the scope of the license belonging to this program, everyone who then obtains this program has all rights, even those granted within the scope of the original software package.
9. The license may not limit distribution together with another software product.
The license may not contain limitations in regard to other software products distributed together with the licensed software. The license, for example, may not demand that all other programs distributed on the same medium must also be Open Source.