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.
For example, on rare occasions, there may be a special need to encourage the widest
possible use of a certain library, so that it becomes a de-facto standard. To achieve this,
non-free programs must be allowed to use the library. A more frequent case is that a free
library does the same job as widely used non-free libraries. In this case, there is little to
