Free software is the software that can be used, studied and modified without restriction. It can be copied and redistributed in the modified or unmodified form either without restriction or with restrictions simply to ensure that end users have the same freedoms as its original authors.
There are many people, who would still consider it mean any “free of cost” software, it comes with the freedoms to use, copy, study, modify and redistribute both modified and unmodified copies of the software programs. To make the software available as free software, it has to be accompanied by a software license saying that the copyright holder allows these acts or be in public domain, and the human readable form of the program must be made available.
Free software allows everyone to sell its copies free, to use the software commercially, and to charge for distribution and modifications. Anyone having a copy may distribute the software at no cost. The free software business models are based on adding value such as support, training, customization, integration, or certification. Although, the free software does not permit for common business models that depend on a user having no choice but to pay for a license in order to lawfully use a software product.
Proprietary software or non-free software is the software that is not free of cost. Free software has a very high market incursion in server-side Internet applications such as Apache web server, MySQL database and PHP scripting language. The completely free computing environments are available as big packages of basic system software such as many GNU/Linux distributions and the Free BSD OS.
