“The promise of the Web is a common framework for exchange of information, with open access for a diverse pool of developers and users. Realization of this promise demands a licensing model that is likewise open and unencumbered by private rights.” — Apple
Copyright and other laws throughout the world automatically extend copyright protection to works of authorship and databases, whether the author or creator wants those rights or not. CC0 gives people who want to give up those rights a way to do so, to the fullest extent allowed by law. Once the creator or a subsequent owner of a work applies CC0 to a work, the work is no longer his or hers in any meaningful legal sense. Anyone can then use the work in any way and for any purpose, including commercial purposes, subject to rights others may have in the work or how the work is used. Think of CC0 as the "no rights reserved" option.
The GNU Lesser General Public License (formerly the GNU Library General Public License) or LGPL is a free software license published by the Free Software Foundation (FSF). It was designed as a compromise between the strong-copyleft GNU General Public License or GPL and permissive licenses such as the BSD licenses and the MIT License.
The license is regarded as a weak copyleft. Specifically, source code copied or changed under the MPL must stay under the MPL. The MPL was approved both as an Open Source software license by the Open Source Initiative and as a Free Software license by the Free Software Foundation.