If you are a beginner, then you should know the difference between Unix and Linux.
Way before Linux, Unix operating systems was desgined at AT&T by Ken Thompson, Denis Ricthie and team. This was back in 1970. You might be surprised to know that Unix is a closed source, properitry operating system. AT&T licensed Unix to various thrid parties, both academic and commercial vendors.
One of the academic vendors is University of California, Berkeley. The Unix operating system developed here is known as BSD (Berkeley Software Distribution). One of the most popular open source derivative of BSD is FreeBSD. Another most popular closed source BSD derviative is Apple’s Mac OS X.
In 1991, Finnish computer science student Linus Torvalds developed his own Unix clone from scratch. This is what we know today as Linux Kernel. Linux distributions add GUI system, GNU utilities (such as cp, mv, ls,date, bash etc), installation & management tools, GNU c/c++ Compilers and various applications on top of the Linux kernel.