This comprehensive article explores the GNU Lesser General Public License 2.1 in depth, providing a detailed summary of its origins, evolution, usage in open source projects, dual licensing support, and challenges. It offers critical insights into how LGPL 2.1 balances free software values with practical commercial applications while comparing it to other licenses such as the MIT License, Apache License 2.0, and the Open Compensation Token License (OCTL). The article is a valuable resource for developers and legal experts navigating modern open source and fair code licensing.