•  What is Open Source ?

Open source is a set of principles and practices that its advocates claim promote access to the design and production of goods and knowledge, overwhelmingly understood as the list of same - the Open Source Definition maintained by the Open Source Initiative. 


It can more correctly be called open source code or open code but those terms are not prevalent. When applied to ordinary-human-readable deliverables that are not machine-executed data, the alternative term open content  are also used. However an open format has source code and so all advantages and debates about open source apply. The Open Source Definition is used by the Open Source Initiative to determine whether or not a software license can be considered open source. The definition was based on the Debian Free Software Guidelines. Under the Open Source Definition, licenses must meet ten conditions in order to be considered open source licenses. Below is a copy of the definition.


  • Free Redistribution: the software can be freely given away or sold. (This was intended to expand sharing and use of the software on a legal basis.)

  • Source Code: the source code must either be included or freely obtainable. (Without source code, making changes or modifications can be impossible.)

  • Derived Works: redistribution of modifications must be allowed. (To allow legal sharing and to permit new features or repairs.)

  • Integrity of The Author's Source Code: licenses may require that modifications are redistributed only as patches.

  • No Discrimination Against Persons or Groups: no one can be locked out.

  • No Discrimination Against Fields of Endeavor: commercial users cannot be excluded.

  • Distribution of License: The rights attached to the program must apply to all to whom the program is redistributed without the need for execution of an additional license by those parties.

  • License Must Not Be Specific to a Product: the program cannot be licensed only as part of a larger distribution.

  • License Must Not Restrict Other Software: the license cannot insist that any other software it is distributed with must also be open source.

  • License Must Be Technology-Neutral: no click-wrap licenses or other medium-specific ways of accepting the license must be required.



Richard Stallman originally accepted Debian's document as a good definition of Free Software, but later created the Free Software definition - in part to differentiate Free Software  from Open Source. In practice, licenses which meet the open source definition almost always also meet the Free software definition. All licenses reported to meet the free software definition as of 2006 also meet the open source definition.

  •  What is Open Source software ?
Open source software is computer software for which the human-readable source code is made available under a copyright license (or arrangement such as the public domain) that meets the Open Source Definition. This permits users to use, change, and improve the software, and to redistribute it in modified or unmodified form. It is often developed in a public, collaborative manner. Open-source software is the most prominent example of open source development and often compared to user generated content.
  •  What is Free Software ?
 Free Software.png

Free software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions only to ensure that further recipients can also do these things. To make these acts possible, the human readable form of the program (called the source code) must be made available. The source code can be placed in the public domain,  accompanied by a software license saying that the copyright holder permits these acts (a free software licence), etc.


The first formal definition of free software written by Richard Stallman is still maintained today and states that software is free software if people who receive a copy of the software have the following four freedoms:


  • Freedom 0: The freedom to run the program for any purpose.

  • Freedom 1: The freedom to study and modify the program.

  • Freedom 2: The freedom to copy the program so you can help your neighbor.

  • Freedom 3: The freedom to improve the program, and release your improvements to the public, so that the whole community benefits.

Freedoms 1 and 3 require source code to be available because studying and modifying software without its source code is highly impractical.


Thus, free software means that computer users have the freedom to cooperate with whom they choose, and to control the software they use. To summarize this into a remark distinguishing libre (freedom) software from grantis (zero price) software, Richard Stallman said: "Free software is a matter of liberty, not price. To understand the concept, you should think of 'free' as in 'free speech', not as in 'free beer'".

  • What is Free software definition ?
The Free Software Definition is a definition published by Free Software Foundation (FSF) for what constitutes free software. The earliest known publication of the definition was in the February 1986 edition of the now-discontinued GNU's Bulletin publication of FSF. The canonical source for the document is on the website of the GNU Project,  in the philosophy section. As of January 2007, it is officially published in 33 languages. FSF publishes a list of licences which meet this definition.
  •  What is Source code ?

Source code (commonly just source or code) is any sequence of statements and/or declarations written in some human readable computer programming language. The source code which constitutes a program is usually held in one or more text files, sometimes stored in databases as stored procedures and may also appear as code snippets printed in books or other media.

A computer program's source code is the collection of files needed to convert from human-readable form to some kind of computer-executable form. The source code may be converted into an executable file by a compiler or executed on the fly from the human readable form with the aid of an interpreter.

  •  What is GNU ?
The GNU Project was launched in 1984 to develop a complete Unix-like operating system which is free software: the GNU system. Variants of the GNU operating system, which use the kernel called Linux, are now widely used; though these systems are often referred to as “Linux”, they are more accurately called GNU/Linux systems. GNU is a recursive acronym for “GNU's Not Unix”; it is pronounced guh-noo, approximately like canoe.
  •  What is Proprietary software ?
Proprietary software is software with restrictions on copying and modifying as enforced by the proprietor. Restrictions on modification and copying are sought by either legal or technical means and sometimes both. Technical means include releasing machine-readable binaries to users and withholding the human-readable source code. Legal means can involve software licensing, copyright, and patent law.
  •  What is Copyright ?
Copyright is a set of exclusive rights that regulate the use of a particular expression of an idea or information. At its most general, it is literally "the rights to copy" an original creation. In most cases, these rights are of limited duration. The symbol for copyright is "©", and in some jurisdictions may alternatively be written as either (c) or (C).
  •  What is Copyleft ?
Copyleft is a play on the word copyright and is the practice of using copyright law to remove restrictions on distributing copies and modified versions of a work for others and requiring that the same freedoms be preserved in modified versions.


Copyleft is a form of licensing and may be used to modify copyrights for works such as computer software, documents. In general, copyright law allows an author to prohibit others from reproducing, adapting, or distributing copies of the author's work. In contrast, an author may, through a copyleft licensing scheme, give every person who receives a copy of a work permission to reproduce, adapt or distribute the work as long as any resulting copies or adaptations are also bound by the same copyleft licensing scheme. A widely used and originating copyleft license is the GNU General Public License.

  •  What is GNU GPL (General Public License) ?

The GNU General Public License (GNU GPL or simply GPL) is a widely used free software license, originally written by Richard Stallman for the GNU project. It is the license used by the Linux kernel. The GPL is the most popular and well-known example of the type of strong copyleft license that requires derived works to be available under the same copyleft. Under this philosophy, the GPL is said to grant the recipients of a computer program the rights of the free software definition and uses copyleft to ensure the freedoms are preserved, even when the work is changed or added to. This is in distinction to permissive free software licences, of which the BSD licenses are the standard examples. The GNU Lesser General Public License (LGPL) is a modified, more permissive, version of the GPL, intended for some software libraries. 

  •  What is BSD license ?

BSD licenses represent a family of permissive free software licences. The original was used for the Berkeley Software Distribution, a Unix-like operating system for which the license is named. The original owners of BSD were the Regents of the University of California because BSD was first written at the University of California, Berkeley. The first version of the license was revised, and the resulting licenses are more properly called modified BSD licenses. Permissive licenses, sometimes with important differences pertaining to license compatibility, are referred to as "BSD-style licenses". Several BSD-like licenses, including the New BSD license, have been vetted by the Open Source Initiative as meeting their definition of open source.


The licenses have few restrictions compared to other free software licenses such as the GNU General Public License or even the default restrictions provided by copyright, putting it relatively closer to the public domain. The BSD licenses have been referred to as copycenter, as a comparison to standard copyright and copyleft free software: "Take it down to the copy center and make as many copies as you want."

  •  What is Public domain software ?

Public domain comprises the body of knowledge and innovation (especially creative works such as writing and inventions) in relation to which no person or other legal entity can establish or maintain proprietary interests within a particular legal jurisdiction. This body of information and creativity is considered to be part of a common cultural and intellectual heritage, which, in general, anyone may use or exploit, whether for commercial or non-commercial purposes. Public domain software is not protected by copyright and may be copied and used without payment.


If an item ("work") is not in the public domain, it may be the result of a proprietary interest such as a copyright, patent, or other sui generis right. The extent to which members of the public may use or exploit the work is limited to the extent of the proprietary interests in the relevant legal jurisdiction. However, when the copyright, patent or other proprietary restrictions expire, the work enters the public domain and may be used by anyone for any purpose.

  •  What is shared software ?
Shared software is a different term used to describe free software and open source software, and possibly also software that is not formally covered by the definition of either, but that is in some other way shared rather than owned. The term has been used to transcend the awkward debate over what to call this type of software.
  •  What is Freeware ?

Freeware is copyrighted computer software which is made available for use free of charge, for an unlimited time. Authors of freeware often want to "give something to the community", but also want to retain control of any future development of the software. Freeware generally refers to software for which the author solicits no payment, even if the user continues to use it.


Freeware is different from shareware, where the user is required to pay (e.g. after some trial period or for additional functionality). Although free software is sometimes used as a synonym for freeware, it is not the same as free software.

  • What is Sharware ?

Shareware software is typically obtained free of charge, often by downloading from the Internet or on magazine cover-disks. A user tries out the program, and thus shareware has also been known as "try before you buy". A shareware program is accompanied by a request for payment, and the software's distribution license often requires such a payment.


The term shareware refers to commercial software that is copyrighted, but which may be copied for others for the purpose of their trying it out with the understanding that they will pay for it if they continue to use it. In contrast, retail software is a term used for commercial software which may not be copied for others.

  • What is Open system ? 
Open systems are computer systems that provide some combination of interoperability, portability, and open software standards. (It can also mean systems configured to allow unrestricted access by people and/or other computers). 


The term describe systems based on Unix, especially in contrast to the more entrenched mainframes and minicomputers in use. Unlike older legacy systems, the newer generation of Unix systems features standardized programming interfaces and peripheral interconnects; third party development of hardware and software.

  •  What is Open standard ?
An open standard is a standard that is publicly available and has various rights to use associated with it. The terms "open" and "standard" have a wide range of meanings associated with their usage. The term "open" is usually restricted to royalty-free technologies while the term "standard" is sometimes restricted to technologies approved by formalized committees that are open to participation by all interested parties and operate on a consensus basis.
  •  What is Open format ?

An open format is a published specification for storing digital data, usually maintained by a non-proprietary standards organization, and free of legal restrictions on use. For example, an open format must be implementable by both proprietary and free/open source software, using the typical licenses used by each. In contrast to open formats, proprietary formats are controlled and defined by private interests. Open formats are a subset of open standards. The primary goal of open formats is to guarantee long-term access to data without current or future uncertainty with regard to legal rights or technical specification. A common secondary goal of open formats is to enable competition, instead of allowing a vendor's control over a proprietary format to inhibit use of competing products. Governments have increasingly shown an interest in open format issues.