First Publication Date: 25th March 2008
The Lesser General Public License(“LGPL”) is a license used by the Free Software Foundation for software libraries. The license governs all open source software libraries of Free Software Foundation and many others who choose to use it. LGPL defines terms and conditions for copying, modification and distribution of software libraries. Version 3 of LGPL incorporates all provisions of the General Public License (“GPL”) and lays down certain additional permissions for software libraries.
A software library governed by version 3 of LGPL is also governed by GPL. Under GPL, a person gets the right to copy, run and distribute the software library governed by it. A person is allowed to distribute verbatim copies of the software library under the following conditions:

  • Source code is made available in any medium;
  • A copy of GPL accompanies the software;
  • A copyright Notice is affixed conspicuously on each copy; and
  • The copyright notices relating to non-existence of A Warranty are kept intact.

The license also allows a person to modify the software library. The modified library may be distributed under the following conditions in addition to the aforementioned conditions:

  • A notice relating to modification and date of modification is incorporated;
  • A notice relating to applicability of GPL and any additional terms is provided; and
  • The entire work along with the modifications is distributed.

Combined Works
An application software using or interfacing with a software library governed by LGPL may be distributed as a combined work under any terms and conditions of choice. However, such terms and conditions should not restrict any modification of the software library that forms part of the combined work. Furthermore, such a distribution should be in accordance with the following conditions:

  • A prominent notice has to be given stating that a software library governed by LGPL is used in the combined work;
  • The combined work has to be transferred with a copy of GPL and LGPL;
  • Copyright notices relevant to the software library have to be incorporated;
  • Source code necessary for using the application software with modified version of the software library has to be provided; and
  • Necessary installation information has to be made available.

Combined Libraries
A library governed by LGPL may be distributed along with another library not governed by LGPL as a combined library. Such distribution should be in accordance with the following terms and conditions:

  • The combined library has to be transferred with a copy of the software and the uncombined software library governed by LGPL and
  • Prominent notice has to be provided stating that the library transferred is a combined library and indicating where the uncombined library governed by LGPL can be acquired.

Terms of GPL
All terms of GPL apply to software libraries governed by LGPL, which provides additional permissions over an above those provided by GPL. Version 3 of LGPL incorporates GPL as a part of the agreement and removes the existing confusion relating to interface with GPL. The provisions of LGPL have been designed as additional terms to GPL, thus removing the scope for conflict between the two agreements.
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