Too Long; Didn't Read
Many users do not understand the difference between the kernel, which is Linux, and the whole system, which they also call “Linux” The ambiguous use of the name doesn't help people understand. Linux is the kernel: the program in the system that allocates the machine's resources to the other programs that you run. Many believe that once Linus Torvalds finished writing Linux, its users looked around for other free software to go with it, and found that (for no particular reason) most everything necessary to make a Unix-like system was already available.