Free software is software for which everyone has the right not only to inspect and study the source code but also to use it for any desired purpose without monetary or other restrictions. These other purposes include making as many copies as desired, installing on as many computers as desired, modifying (including extending) in any desired way, and redistributing in its original or modified form.
As defined by Free Software foundation, its a software whose licensing conditions promise following 4 freedoms
* Freedom 0: freedom to run the program for any purpose. Eg. Softwares restricted for educational use hinders this freedom (like those distributed under MicroSoft Academic Alliance)
* Freedom 1: freedom to study how the program works, and change it to make it do what you wish. Eg. Softwares whose licensing terms forbids reverse engineering curtails this freedom
* Freedom 2: freedom to redistribute copies. Eg. softwares (eg. WinXP) whose licensing terms forbids copying of software and using it on multiple systems curtails this freedom.
* Freedom 3: freedom to improve the program, and release your improvements (and modified versions) to the public. Eg. freewares which can be downloaded for free (of cost) but modifying them and then distributing modified copy is violation of license agreement (hence, violating copyright law).
2. Open-Source Software Open source software is software whose source code is freely available for anyone to inspect and study. A free software is always also open source, open source software does not necessarily have to be free software.
3. Free and Open-Source Software : When a software combines the above two features, the same can be said to fall under the category of FOSS. Wikipedia : Its a software that is liberally licensed to grant the right of users to use, study, change, and improve its design through the availability of its source code.
So, on the closing note a free software is more about “freedom” rather than zero-price.
Source : Wikipedia,opensource.org,linfo.org,ashishb.net