"In 1991, while attending the University of Helsinki, Torvalds became curious about operating systems[31] and frustrated by the licensing of MINIX, which limited it to educational use only. He began to work on his own operating system which eventually became the Linux kernel.
Torvalds began the development of the Linux kernel on MINIX and applications written for MINIX were also used on Linux. Later, Linux matured and further Linux kernel development took place on Linux systems.GNU applications also replaced all MINIX component" http://en.wikipedia.org/wiki/Linux#Creation
"In 1991, while attending the University of Helsinki, Torvalds became curious about operating systems[31] and frustrated by the licensing of MINIX, which limited it to educational use only. He began to work on his own operating system which eventually became the Linux kernel.
Torvalds began the development of the Linux kernel on MINIX and applications written for MINIX were also used on Linux. Later, Linux matured and further Linux kernel development took place on Linux systems.GNU applications also replaced all MINIX component" http://en.wikipedia.org/wiki/Linux#Creation