A little history: Linux


The Linux kernel comes from the Minix (mini-unix) experience
and has been written for fun by Linus Torvalds on his 386
computer with 4MB of RAM memory, in order to learn
how multitasking works and to overcome the Minix limitations.

The main features of the system are:

Unix compatibility at functional level
Unix compatibility at source level
GNU GPL license for kernel code
Support for dozens of platforms (over time)