In 1991, Linus Torvalds, a student in Finland, made an innocent post to an e-mail group. He wrote that he was working on a free version of UNIX, an operating system that had been in use for twenty years. The Torvalds version, which came to be called Linux (Linus UNIX), was released under an agreement called the General Public License. In essence, anyone could use Linux in any way and modify it in any way, as long as any changes made were not hidden or charged for. This ensured that Linux would remain “open.”
“Windows versus Linux” has become the main battleground in the larger war of “proprietary versus open-source.” Adherents on both sides believe their approach will lead to more effective software.
Source of Information : Broadway-Computer Science Made Simple 2010