In 1969 Ken Thompson developed UNIX in bell laboratories. The UNIX operating system was developed basically using the c programming language.
Later the years passed on several operating systems are developed using the UNIX some of them are HP-UX, Apple computer’s A/UX, IBM’s AIX etc.,
In 1990’s Linus Torvalds, a graduate student from the University of Helsinki designed a kernel on 80386 Intel machine and gave this to OSF (Open Source Foundation).
From his name the kernel was named as Linux kernel. By collaborating this kernel with the GNU applications a complete UNIX like os was developed and that is called Linux OS.
Linus' UNIX -> Linux
The good competitors of Linux were windows, Solaris, IBM-AIX, HP-UX etc.