When we speak of free software, we are referring to freedom of use, not price. Our General Public
Licenses are designed to make sure that you have the freedom to distribute copies of free software (and
charge for this service if you wish); that you receive source code or can get it if you want it; that you can
change the software and use pieces of it in new free programs; and that you are informed that you can
do these things.
To protect your rights, we need to make restrictions that forbid distributors to deny you these rights or to
ask you to surrender these rights. These restrictions translate to certain responsibilities for you if you
distribute copies of the library or if you modify it.
For example, if you distribute copies of the library, whether gratis or for a fee, you must give the
recipients all the rights that we gave you. You must make sure that they, too, receive or can get the
source code. If you link other code with the library, you must provide complete object files to the
recipients, so that they can relink them with the library after making changes to the library and
recompiling it. And you must show them these terms so they know their rights.
We protect your rights with a two-step method: (1) we copyright the library, and (2) we offer you this
license, which gives you legal permission to copy, distribute and/or modify the library.
To protect each distributor, we want to make it very clear that there is no warranty for the free library.
Also, if the library is modified by someone else and passed on, the recipients should know that what they
have is not the original version, so that the original author's reputation will not be affected by problems
that might be introduced by others.
Finally, software patents pose a constant threat to the existence of any free program. We wish to make
sure that a company cannot effectively restrict the users of a free program by obtaining a restrictive
license from a patent holder. Therefore, we insist that any patent license obtained for a version of the
library must be consistent with the full freedom of use specified in this license.
Most GNU software, including some libraries, is covered by the ordinary GNU General Public License.
This license, the GNU Lesser General Public License, applies to certain designated libraries, and is quite
different from the ordinary General Public License. We use this license for certain libraries in order to
permit linking those libraries into non-free programs.
When a program is linked with a library, whether statically or using a shared library, the combination of
the two is legally speaking a combined work, a derivative of the original library. The ordinary General
Public License therefore permits such linking only if the entire combination fits its criteria of freedom. The
Lesser General Public License permits more lax criteria for linking other code with the library.
We call this license the "Lesser" General Public License because it does Less to protect the user's
freedom than the ordinary General Public License. It also provides other free software developers Less
of an advantage over competing non-free programs. These disadvantages are the reason we use the
ordinary General Public License for many libraries. However, the Lesser license provides advantages in
certain special circumstances.
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