Copyright arises and starts to belong to the creator of a work from the moment of the completion of that work without the need for any registrations or other explicit acts or indications from the latter. These rights are of exclusive character since they arise and belong only to the author of the work who can seek protection if any of those rights is exercised by a third party without the author’s authorization. However, authors rarely exercise their exclusive rights by themselves but often seek large scale production, distribution and use of their works, since thus a significantly larger income from the work will be produced in their favour. But, in order for a third party to rightfully exploit the protected work (including reproduction, distribution, etc.), a contractual agreement in the form of a license with the author must be struck.

Open source licenses are specific types of contractual agreements which aim to eliminate all kinds of exclusivity on the exploitation of the work at hand. Open source licenses may regard not only computer software but other products as well. Typically, when an individual acquires a computer software product which is protected by copyright, the individual gains a separate copy of the program on a physical (DVD, CD, etc.) medium or utterly digital (i.e. by a download). Alongside this copy, the user enters into a contractual agreement with the copyright holder which obliges the user not to make additional copies of the work, distribute it to third parties or make any alterations or derivatives of the code. In comparison, open source licenses postulate that the user can freely distribute copies of the software code (open distribution), freely alter and modify the source code and distribute her own versions of it (open modification), provided the user distributes all kinds of copies under the same terms under which the user was provided access to the work in the first place. This so called ‘generational limitation’ ensures that the original source code and all further modifications made remain available to the public domain and do not ‘go closed’.

These characteristics of open source provide the model with several advantages over the traditional proprietary software approach.

First of all, open source is characterized with considerable reliability. In accordance with Linus Torvalds’ law formulated in Eric S. Raymond’s book “The Cathedral & the Bazaar”(1999): “given enough eyeballs, all bugs are shallow”. A large base of developers who can review the source code can render a software product highly ‘vulnerability-proof’.

Secondly, open source creates a strong element of innovation to a software product since developers have proved to be willing to contribute to software projects often without any monetary remuneration in return.

Last but not least, open source licenses allow a software product to benefit from a considerably longer lifecycle. When the owners of a commercially licensed software discontinue their support for whatsoever reasons, the software product reaches the end of its lifecycle and may even end up with considerable vulnerabilities in the near future due to its outdated security. Conversely, open source licenses allow for a product to be constantly rewritten, revised and improved as long as the open source community retains interest in doing so.

In pursuit of the aforementioned benefits, entities have come up with various open source licenses which allow the average consumer to freely run the program, study and modify the program’s source code, distribute the software product and its modifications, but oblige him not to discriminate against persons, groups, fields of endeavour and redistribute the derivatives under the original license. In order for a license to qualify as open source it should fall under the definition given by the Open Source Initiative (OSI), which also certifies licenses as OSI Certified to indicate that they fall within the given definition. OSI gives 10 points a license must meet in order to qualify as open source:

1.Free Redistribution. The license shall 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 shall 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 explicitly 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 Endeavour. The license must not restrict anyone from making use of the program in a specific field of endeavour. 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 Restrict 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.

10.License Must Be Technology-Neutral. No provision of the license may be predicated on any individual technology or style of interface.