• Linux is the kernel of an operating system.
• Linux was built on the Unix tradition.
• Linux was originally developed by Linus Torwalds of Finland, who currenctly owns the Linux trademark.
• Linux stands for Linus' Unix.
• Using the open source code of the Linux kernel, people have been developing operating systems based on the Linux kernel. These are called the "Linux distributions".
  

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Linux, the Ultimate Unix
Linux was developed based on the Unix tradition. But it is not just another Unix flavor. It has turned the evolution of Unix into a revolution. Learn more here.