Open source software relies on valid open source licenses and gives users four essential freedoms: to run the program for any purpose, study and modify the source code, redistribute copies to help others, and release improvements to benefit the community. While public domain status allows sharing, it also allows proprietary conversion. Copyleft licensing requires derived works to also be free and open. Creative Commons licenses allow modifying copyright terms to suit needs along a spectrum from full copyright to public domain. Popular open source licenses include GPL, LGPL, Apache 2.0, BSD, MIT and MPL.

1. OPEN SOURCE AND COPYRIGHTOpen source is a development method for software that harnesses the power of distributed peer review and transparency of process. All the open source models depend, in a large proportion, on the validity of open source licenses, in case they are at some point challenged in courts.

2. Software is considered “open source” if its distribution terms are open and free. Free software is a matter of the users' freedom to run, copy, distribute, study, change and improve the software.

3. Program's users should have the four essential freedoms: 1. The freedom to run the program, for any purpose2. The freedom to study how the program works, and change it to make it do what you wish. Access to the source code is a precondition for this. 3. The freedom to redistribute copies so you can help your neighbor. 4. The freedom to improve the program, and release your improvements (and modified versions in general) to the public, so that the whole community benefits.

4. Copyright law, by default, do not allow for redistribution (nor even use) of software. MOVIE

5. PUBLIC DOMAINThe simplest way to make a program free software is to put it in the public domain, 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 proprietary 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.

6. OPEN SOURCE / FREE SOFTWARE LICENSES

7. GNU / COPYLEFTCopyleft = license requiring all modified and extended versions of the program to be free as well. When redistributing the program, you cannot add restrictions to deny other people the central freedoms. To copyleft a program, you first state that it is copyrighted; then add distribution terms, which are a legal instrument that gives everyone the rights to use, modify, and redistribute the program's code, or any program derived from it, but only if the distribution terms are unchanged. The code and the freedoms become legally inseparable.

8. FREE SOFTWARE FOUNDATIONThe Free Software Foundation (FSF) is a nonprofit with a worldwide mission to promote computer user freedom and to defend the rights of all free software users.Promoting the development and use of free software and documentation and by campaigning against threats to computer user freedom like Digital Restrictions Management (DRM).(you can find list of all licenses on their web site)

9. CREATIVE COMMONS LICENSESCreative Commons defines the spectrum of possibilities between full copyright and the public domain. ALL RIGHTS RESERVED / SOME RIGHTS RESERVED / NONE RIGHTS RESERVEDThis licenses are not an alternative to copyright. They work alongside copyright, so you can modify your copyright terms to best suit your needs. THE COMMONSThey created online database — the body of work that is available to the public for free and legal sharing, use, repurposing, and remixing.

10. OPEN SOURCE INITIATIVEThe community-recognized body for reviewing and approving licenses as OSD-conformant.The OSI is actively involved in Open Source community-building, education, and public advocacy to promote awareness and the importance of non-proprietary software.

11. OPEN RIGHTS GROUPOpen Rights Group is the UK’s leading voice defending freedom of expression, privacy, innovation, consumer rights and creativity on the internet. We campaign to change public policy whenever citizens' or consumers' rights are threatened. We do this by talking to policy-makers and mobilising our supporters to stop bad laws in the UK and EU

12. License that are popular and widely used GNU General Public LicenseGNU Library General Public LicenseApache License, 2.0New and Simplified BSD licensesMIT licenseMozilla Public LicenseCommon Development and Distribution LicenseEclipse Public License

13. Shareware is software which comes with permission for people to redistribute copies, but says that anyone who continues to use a copy is required to pay a license fee. Proprietary software is software that is not free or semi-free. Its use, redistribution or modification is prohibited, or requires you to ask for permission, or is restricted so much that you effectively can't do it freely. Freeware are packages which permit redistribution but not modification (and their source code is not available). These packages are not free software!Semi-free software is software that is not free, but comes with permission for individuals to use, copy, distribute, and modify (including distribution of modified versions) for non-profit purposes.

14. Resourceshttp://www.fsf.orghttp://www.opensource.orghttp://creativecommons.orghttp://www.wipo.inthttp://eu.conecta.it/paper/Open_source_copyright_law.htmlhttp://www.openrightsgroup.orgMirnaRaduka, Open Source Design, Parsons 2009