The licenses for most software and other practical works are designed to take away your freedom to share and change the works. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program--to make sure it remains free software for all its users. We, the Free Software Foundation, use the GNU General Public License for most of our software; it applies also to any other work released this way by its authors. You can apply it to your programs, too.
Copyright to author http://www.gnu.org/licenses/gpl.html
Free: It can be copied and distributed without fees or royalties. The source code for Linux is available on the Internet to anyone who wants it. You can also purchase copies from different Linux distributors. What Are These "Distributions?" A number of companies are selling Linux. Their versions, called distributions , may still be retrieved freely over the Internet, as well as cheaply or freely on CDROM discs, but the packaged versions have the advantage of often being bundled with commercial application programs (word processors, etc.), a large manual, and technical support. Sometimes you'll hear people abbreviate distribution as ` distro .' When it comes to stability and price, Linux is an excellent choice for running a server . A server is a computer that makes resources (such as web pages, a shared printer, shared files, etc.) available to users on other computers in a network (like the Internet, or a small network in an office). most desktops use Microsoft Windows and most supercomputers use Linux. The development of Linux is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified, and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License . Typically Linux is packaged in a format known as a Linux distribution for desktop and server use. Some popular mainstream Linux distributions include Debian (and its derivatives such as Ubuntu ), Fedora and openSUSE . Linux distributions include the Linux kernel, supporting utilities and libraries and usually a large amount of application software to fulfill the distribution's intended use. Linux runs on a wide variety of computer hardware, including mobile phones, tablet computers, routers, televisions  , video game consoles, desktop computers, mainframes and supercomputers.  Linux is a leading server operating system, and runs the 10 fastest supercomputers in the world. 
Introduction to Linux
An IntroTo ThePenguin(Linux)
Linus TorvaldsStudent at theUniversity of HelsinkiDOS inadequateUNIX expensivei3861992 : version 0.12
In 1994 Torvaldsreleased the LinuxKernel.This is the heart of all Linuxsystems and is developedand released under the GNUGeneral Public License.
Thousands of programmers began working to enhance Linux,This is the heart of all Linuxsystems and is developedand released under the GNUGeneralthe OS grew and And Public License. improvedrapidly and freely.
Linux system is … Robust Adaptable Functional Freely distributed
Linux Ads• Evolution• Linux Is Working (IBM)• Muhammad Ali (IBM)
Things You Should Know• It is Free (as in beer and as in freedom)• Linux is a leading server operating system and runs the 10 fastest supercomputers in the world.• The development of Linux is one of the most prominent examples of free and open source software collaboration• Linux runs on various platforms