Sony HDR-AS15 - Manual (Page 156)

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 gain by limiting the free library to
free software only, so we use the Lesser General Public License.
In other cases, permission to use a particular library in non-free programs enables a
greater number of people to use a large body of free software. For
example, permission to use the GNU C Library in non-free programs enables many
more people to use the whole GNU operating system, as well as its
variant, the GNU/Linux operating system.
Although the Lesser General Public License is Less protective of the users' freedom, it
does ensure that the user of a program that is linked with the
Library has the freedom and the wherewithal to run that program using a modified