What is open source The basic idea behind open source is very simple. When programmers on the Internet can read, redistribute, and modify the source for a piece of software, it evolves. People improve it, people adapt it, people fix bugs. The open-source community have learned that this rapid evolutionary process produces better software than the traditional closed model, in which only a very few programmers can see source and everybody else must blindly use an opaque block of bits. Open source doesn't just mean access to the source code. The distribution terms of open-source software must comply with the following criteria: 1.
Free Redistribution-The license may not restrict any party from selling or giving away the software as a component of an aggregate software distribution containing programs from several different sources. The license may not require a royalty or other fee for such sale. 2. Source Code-The program must include source code, and must allow distribution in source code as well as compiled form.
Where some form of a product is not distributed with source code, there must be a well-publicized means of obtaining the source code for no more than a reasonable reproduction cost - preferably, downloading via the Internet without charge. The source code must be the preferred form in which a programmer would modify the program. Deliberately obfuscated source code is not allowed. Intermediate forms such as the output of a preprocessor or translator are not allowed. 3. Derived Works-The license must allow modifications and derived works, and must allow them to be distributed under the same terms as the license of the original software.
4. Integrity of The Author's Source Code. -The license may restrict source-code from being distributed in modified form only if the license allows the distribution of "patch files" with the source code for the purpose of modifying the program at build time. The license must explicit permit distribution of software built from modified source code. The license may require derived works to carry a different name or version number from the original software.
5. No Discrimination Against Persons or Groups. -The license must not discriminate against any person or group of persons. 6. No Discrimination Against Fields of Endeavor. -The license must not restrict anyone from making use of the program in a specific field of endeavor.
For example, it may not restrict the program from being used in a business, or from being used for genetic research. 7. 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. 8.
License Must Not Be Specific to a Product. -The rights attached to the program must not depend on the program's being part of a particular software distribution. If the program is extracted from that distribution and used or distributed within the terms of the program's license, all parties to whom the program is redistributed should have the same rights as those that are granted in conjunction with the original software distribution. 9. License Must Not Contaminate Other Software. -The license must not place restrictions on other software that is distributed along with the licensed software.
For example, the license must not insist that all other programs distributed on the same medium must be open-source software. What is CopyLeft The simplest way to make a program free is to put it un copyrighted. This allows people to share the program and their improvements, if they are so minded. But it also allows uncooperative people to convert the program into propreitary software. They can make changes, many or few, and distribute the result as a proprietary product. People who receive the program in that modified form do not have the freedom that the original author gave them; the middleman has stripped it away.
In the Gnu project the aim is to give all users the freedom to redistribute and change GNU software. If middlemen could strip off the freedom, we might have many users, but those users would not have freedom. So instead of putting GNU software in the public domain, we "copyleft" it. Copyleft says that anyone who redistributes the software, with or without changes, must pass along the freedom to further copy and change it. Copyleft guarantees that every user has freedom.
Copyleft also provides an incentives for other programmers to add to free software. Important free programs such as the GNU C++ compiler exist only because of this. Copyleft also helps programmers who want to contribute improvements to free software get permission to do that. These programmers often work for companies or universities that would do almost anything to get more money.
A programmer may want to contribute her changes to the community, but her employer may want to turn the changes into a proprietary software product. Is Linux software always free linux software the o. s is free but other software such as applications for linux is not, there are free trials of many of their software but there are retailers that do sell linux software.