Open source

Open source or open-source is the idea that source code for a piece of software is freely available for viewing and modifying. According to the Open Source Definition, the following ten conditions must be met to be considered "open source":

1. Free Redistribution: the software can be freely given away or sold. (This was intended to expand sharing and use of the software on a legal basis.)
2. Source Code: the source code must either be included or freely obtainable. (Without source code, making changes or modifications can be impossible.)
3. Derived Works: redistribution of modifications must be allowed. (To allow legal sharing and to permit new features or repairs.)
4. Integrity of The Author's Source Code: licenses may require that modifications are redistributed only as patches.
5. No Discrimination Against Persons or Groups: no one can be locked out.
6. No Discrimination Against Fields of Endeavor: commercial users cannot be excluded.
7. Distribution of License: The rights attached to the program must apply to all to whom the program is redistributed without the need for execution of an additional license by those parties.
8. License Must Not Be Specific to a Product: the program cannot be licensed only as part of a larger distribution.
9. License Must Not Restrict Other Software: the license cannot insist that any other software it is distributed with must also be open source.
10. License Must Be Technology-Neutral: no click-wrap licenses or other medium-specific ways of accepting the license must be required.

The MIT/X11 License is an example of an open source license.