GNU
General Public License is the widely used license for free software
which ensures the users the right to study, copy, alter and share the
softwares. Softwares that acquires
these rights are called Free software. This License is first released
by Richard Stallman of the Free Software Foundation(FSF)
for GNU Project in 1989.
This license is based on the copyleft principle. i.e, the chain of
users involved should distribute their work or modifications that
he/she has done to the software under the same license. It is the
first copyleft license for general use.
The
GPL accounted for nearly 65% of the 43,442 free
softwares
projects
listed on
Freecode as of August 2007
and
about 68% of the projects listed on
SourceForge.net by
January 2006.
Most widely used free software that are licensed under GPL includes
Linux Kernel and GNU Compiler Collection(GCC). There
are also some
dual licensed free
softwares
like MySQL in
which
one being the GPL.
On
29 June 2007, the third new version of the license(GNU GPLv3) was
released
to solve the issues that GNU GPLv2
had. To
keep the GPL updated, developers has the option to choose “any
later version” clause. This is to choose between the original terms
or terms imposed by the new version imposed
by FSF. For
example Linux Kernel is under GPLv2 without “any later version”
clause.
Now
let's see the different versions of the GPL
Version
1
The
first version of GPL was released on 25th
February 1989. It was mainly published to prevent the restrictions
that violated the definition of the Free software. The
first problem that GPL solved is that, the distributors were asked to
produce the human readable form of the source code along with the
binaries under the same licensing conditions.
The
second problem was that vendors imposed additional restrictions
to
the license and
combined softwares with other which had other restriction on its
distribution. To avoid this GPLv1 said that altered or modified
software as a whole has to be distributed under same conditions.
Version
2
According
to Stallman, the prominent change in GPLv2 was “Liberty or Death”.
It
states that, restrictions that prevent
him
or her from distributing GPL licensed software in a way that respects
other users' freedom, he or she cannot distribute it at all.
Version
3
GPLv3 was released on 29th
June 2009 by Richard Stallman with
legal counsel from Eben Moglen and the Software Freedom Law Center.
The
major changes in GPLv3 are in relation to free software, software
patents, “source code” definition and hardware restrictions on
software modification.
GPLv3
improves
compatibility with several open source software licenses such as
Apache License, version 2.0.
It
was a long journey when they finally published the third version
GPLv3 on 29th
June 2009.
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