Software Licenses

 
 
To understand software licenses, you first need to understand the rights that can be granted to the holder of a copyright (= copyright owners). These rights are:
  1. The exclusive right to reproduce copyrighted works.

    The copyright owners have the exclusive right to copy the copyrighted software, document, sound, image, etc. on a storage device (CDROM, disk, etc).

  2. The exclusive right to make derivative works.

    The copyright owners have the exclusive right to modify (= annotate, edit, translate, etc.) software, document, sound, image, etc. By these modifications a derivative work is created.

  3. The exclusive right to distribute the work.

    The copyright owners have the exclusive right to distribute legitimate copies of software, document, sound, image, etc.

  4. The exclusive right to perform the work publicly.

    The copyright owners have the exclusive right, to publicly perform motion pictures, audiovisual works, musical, etc.

  5. The exclusive right to display the work.

    The copyright owners have the exclusive right, to show a copy of the work either directly or indirectly on a device or process. For example screen shots of a motion picture is shown on television, magazine, news paper, etc.

Anything that is not public domain has a copyright even if there is no copyright notice. By using a software license the author of the code(= copyright owner) specifies the rights (see points 1 to 5 mentioned above) under which the software is legally to be used by users.

There are many software licenses and a complete overview can be found at:
http://www.opensource.org/licenses/

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Quick reference






Open source licenses.



The most important open source software licenses are mentioned here below and are listed from least restrictive to most.


License Business Impact
Public Domain The software is free to copy, modify, publish, use, compile, sell, or distributed, either in source code form or as a compiled binary, for any purpose, commerical or non-commerical, and by any means.

You are free to make changes to the software and keep those changes proprietary. You can even choose to charge for the original code or a derivative, without providing access to the source code at all.

Note: To put software in the public domain include the following line at the head of each file:

Placed in public domain by John Doe, 2003. Share and enjoy!
GNU Lesser General Public License
(LGPL)
  • The LGPL software is free to use.
  • If the LGPL software is modified the source code must be made available if redistributed.
  • The LGPL software can be included within a larger proprietary software package.
  • If the LGPL software is modified and is used by the proprietary software package then the source code of the proprietary software does not need to be made available if redistributed.
The GNU General Public License
(GPL)
  • GPL software is free to use.
  • If the GPL software is modified the source code must be made available if redistributed.
  • The GPL software can be included within a larger proprietary software package.
  • If the GPL software is MODIFIED and is used by the proprietary software package then the source code of the proprietary software MUST be made available if redistributed.
  • If the GPL software is NOT MODIFIED and is used by the proprietary software package then the source code of the proprietary software does NOT need to be made available if redistributed.