Knowledge and its application have become global more these days than it had ever been before. Before the Renaissance knowledge has been the exclusive monopoly of the privileged class. Free software envisages a society where knowledge is freely flowing without any constraints.
The Free Software Foundation established in 1985, is dedicated to promoting computer user's rights to use, study, copy and redistribute computer programs. By definition, free software implies four different kinds of freedom
1.    The freedom to use the program
2.    The freedom to study how the program works and adapt it to the requirements of the user. Access to the source code is a precondition to this.
3.    The freedom to redistribute the program so that it benefits to another user.
4.    The freedom to modify or improve the program and release it to the public so that society at large is benefited.

What is free software
Knowledge and its application have become global more these days than it had ever been before. Before the Renaissance knowledge has been the exclusive monopoly of the privileged class. Free software envisages a society where knowledge is freely flowing without any constraints.
The Free Software Foundation established in 1985, is dedicated to promoting computer user's rights to use, study, copy and redistribute computer programs. By definition, free software implies four different kinds of freedom
1.    The freedom to use the program
2.    The freedom to study how the program works and adapt it to the requirements of the user. Access to the source code is a precondition to this.
3.    The freedom to redistribute the program so that it benefits to another user.
4.    The freedom to modify or improve the program and release it to the public so that society at large is benefited.
Hence a program is Free Software if users have all these freedoms. Thus we should be free to redistribute copies either with or without modifications, either free of cost or charging a fee for distribution, to anyone anywhere. We all know that any kind of modification to software is possible only when we have access to the source code of that program. What we now see is that any available program of software giants not only charges heavily and put a lot of copyright rules; it also does not provide access to the source code hindering adaptability of the program for individual cases. So accessibility to the source code is an essential requisite for labeling any program as Free Software. Similarly, the developer of the software should not have the right to revoke the license of any person as long as he does not use it for wrong purpose. By free software what is meant is the freedom the user has with regard to all kinds of changes. Free software does not exclusively refer to those things which one gets free. If we do not have the freedom to use the software in all aspects, it is not free whether we pay money to get it or not. The basic concept is how flexible a program is in its being user-friendly.
The brain behind the concept of free software, Richard M. Stallman, is a former student of Harvard University. He later associated himself with Massachusetts Institute of Technology in its Artificial Intelligence lab. Since then he is working for the free software project, particularly the GNU operating system.
Evolution of Linux
Linux is an operating system that was initially created as hobby by a young student, Linus Torvalds, at the University of Helsinki in Finland. Linux is developed under the GNU General Public license and its source code is freely available to everyone. This however doesn't mean that Linux and its assorted distributions are free. Companies and developers may or may not charge money for it, but the source code will have to remain available.
Due to the very nature of Linux's functionality and availability, it has become quite popular world wide and a vast number of software programmers have taken Linux's source code and adapted it to meet their individual needs.
Linux is a reliable and secure operating system. In addition to being cost effective, it is constantly being updated and refined with latest technologies. As Linux gains greater acceptance through out the computing industry, more and more companies are supporting Linux via both application and hardware compatibility.
Linux is available in several formats called distributions. Each distribution has its own set of features and functionality that makes it unique. Some distributions are available to download at no charge, others are provided on CD or floppy disks and have nominal charge associated with them.
Applications of Linux Operating System
Linux is used for a wide variety of purposes including networking, software development and as an end-user platform. Linux is often considered as excellent, low cost alternative to other more expensive operating systems.
The above network diagram shows different applications of Linux operating system in a network. In this LAN, Linux is used as a Mail server, Web Server and Database server. Linux' SendMail(MaiServer), Apache(Web Server) and MySQL(Database Server) applications are well known and widely used all over the world. All these Linux servers can co-exist with Servers running Windows operating systems.
The client PCs are using Linux as end-user operating system. A very user friendly graphical user interface (GUI) is available with Linux now a days which can meet all the requirements of office as well as home users. Secure Internet access can be provided to all users of the network through a Linux firewall PC, a PC with two network cards and Linux operating system, which acts as a full fledged firewall. Hence Linux is used to meet almost all requirements of the computing industry.
Free Software helps us to chalk out programs adaptable to any kind of requirement.  We move from a rigid and dependent condition to a highly flexible and independent state.  With the success of Free Software Movement we can hope for a great revolution in the expansion of the horizons of knowledge.