The GNU General Public License (GPL) is a series of widely used free software licenses that define the terms under which source code can be distributed and modified. Its historical relevance lies in establishing a legal framework that guarantees users the freedom to run, study, share, and improve software, marking a turning point in open-source development philosophy against the proprietary model. This legal document has been fundamental to the creation of ecosystems like Linux and has influenced the preservation of technical knowledge by allowing inspection and community collaboration. Its widespread adoption transformed the understanding of copyright in the digital realm, offering a viable alternative to the total restriction of source code access that dominated the industry during the 1980s and 1990s.