Epson PowerLite Pro Z8050WNL Guide D'utilisation Réseau page 70

Remarques générales
70
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 version of the Library.
The precise terms and conditions for copying, distribution and modification
follow. Pay close attention to the difference between a "work based on the
library" and a "work that uses the library". The former contains code derived
from the library, whereas the latter must be combined with the library in
order to run.