The LGPL was first released as Version 2.1 in February of 1999. It was the follow-up license to the GNU Library General Public License 2.0. Under its old name, the FSF (Free Software Foundation) felt that the license was too often used inappropriately.
The key difference between the GPL and LGPL licenses is that software or a library under the LGPL can be "linked to" or "used by" either a GPL-licensed or a proprietary program.
This program can then be distributed to users without worrying with the GPLs requirements that the LGPL-licensed part of the code be freely available to other developers. The code that is not covered by the LGPL, however, doesnt need to be shared.