What is Open Source?
Open Source is a philosophy regarding software copyright under which one software developer is granted permission to use another developer’s code without having to individually ask permission. It may also refer to the genre of software that encompasses that philosophy and utilizes open source licensing.

Why is Open Source good?
There may be several reasons why a developer may favor the Open Source philosophy. Primarily, Open Source fosters creativity. Software products can often require an overwhelming amount of code for one individual or even a few individuals to write, especially if all that code needs to be original so that it does not infringe on another person’s copyright. This may not be a problem for large companies with armies of engineers. But this can be an insurmountable hurdle for individuals or smaller groups. Open source licensing enables developers not only by providing sets of code that can be appropriated towards their final vision, but it also enables others to actively contribute to or improve upon another developer’s product.

A great metaphor for the effect of Open Source is Wikipedia.org. Wikipedia’s content is licensed under a Creative Commons license, which achieves the same goals as open source software licenses. Much like encyclopedia volumes, which are collections of articles that contribute to the whole set, software products may be seen as a collection of coded functions. Traditionally, each article of an encyclopedia is written by a small number of employees of the encyclopedia company. Then came Wikipedia. Any person can contribute to almost any article. The result became a go-to resource that cannot be matched in depth, breadth or currentness by any one publisher. Likewise, any of the information may be used freely by any reader as long as they comply with the Attribution and Share Alike conditions of the license (see below).

How does Open Source work with traditional copyright?
It is important to recognize that copyright laws are in full effect when participating in Open Source software. All software, regardless of whether a developer makes it Open Source, automatically vests a copyright with the author of that software as soon as it is written out. This copyright protects the author’s control over how that work is used by others. Copyright owners that choose to allow their source code to be used freely by others may apply an open source license to their source code. The text of the license included in the software usually contains conditions that control how that software may be used. Remember: if there is no license text included in the source code, a readme file, or other similar text, then it is copyrighted material and may not be used without express permission from the author.

How do I know if a license is an Open Source license?
The Open Source Initiative [hyperlink to http://www.opensource.org] (“OSI”) created the Open Source Definition [hyperlink to http://www.opensource.org/osd] (“OSD”) which outlines ten criteria for a license to be deemed Open Source. If you agree with goals of Open Source, it is best to use a license that has already been approved by the OSI.

It is possible for a license to not meet all of the criteria of the OSD, while still permitting the public to freely use the source code. Such a license would tend to restrict certain uses of the code, while freely allowing other uses. For example, to meet the OSD, a license must not prohibit a subsequent user from using the code in a certain industry. This does not mean that a licensor can never legally restrict such a use. It merely means that it does not meet the OSD. While that may be frowned upon by the Open Source community, it is certainly legal.

What are some common conditions contained in Open Source Licensing?
This is by no means an exhaustive list, but some of the larger issues include:
Attribution - Most licenses require that the next users provide notice in the derivative work acknowledging that their code contains another’s open source code and who is the creator or source of that code.
Reciprocation/Share Alike - Some licenses requires the next developer to apply the same license to the derivative work. Commonly, this takes place when a licensor wants anyone taking advantage of her work to give the subsequent work back to the open source community, or perhaps even to provide for free use and distribution to the public at large. Reciprocation is a common vehicle used by proponents of Copyleft or Free Software movements to achieve their goal of perpetual gratuity. There is an ideological split in the Open Source community on this element, depending on how each person perceives the intended benefits of Open Source.
Disclaimer of warranties. Almost every license carries a disclaimer stating that the code is provided “as is,” and that there is no guaranty that it will work or that lit does not infringe on another’s copyright. In other words, the licensor makes no warranty of merchantability, no warranty for fitness for a particular purpose, and no warranty for non-infringement. This is essential for allowing a licensor to publish or permit use of her code without the fear that it will be misused.
Use of Trademarks - Licensors typically restrict the next user’s use of the licensor’s trademarks so that no one will confuse the licensor as endorsing the next user’s products.
Publication - Some licenses require you make your code available for public viewing. Conversely, other licenses will allow use of the code for private use.

Can you give me an example of some common licenses?
A great resource for information on the differences between specific licenses is choosealicense.com [hyperlink to http://choosealicense.com/licenses/]. They provide more than a dozen examples of the most common software licenses, which can be directly copied and applied to a developer’s software.

What is a Creative Commons license?
Creative Commons licenses are very similar to open source licenses. Unlike open source licenses, they are applied to copyrightable material outside of the software medium, like photography, video, music, or text. Also, some of their licenses do not meet the OSD because they restrict certain uses. Visit the Creative Commons website [hyperlink to http://creativecommons.org/] for information on their stock licenses and for some powerful examples [hyperlink to http://creativecommons.org/who-uses-cc] of how their licenses have been used.

What does someone looking to use someone else's source code need to know?
The first thing you should know is that If you can't find the license in their code, then traditional copyright and patent laws apply. Also, alway look at the actual language of the license to know what type of use is permitted and what conditions must be met. Lastly, just because you used open source code in your product doesn’t mean that you are free from infringement claims. For example, there might be a patent that the licensor didn’t know about. So, insurance and due diligence are still important and relevant concepts when using Open Source.

“Open Source Licensing FAQ” by Justin G. La is licensed under a Creative Commons Attribution 3.0 Unported License.

Open Source Licensing FAQ by Justin G. La is licensed under a Creative Commons Attribution 3.0 Unported License.

Bibliography
Rosen, Lawrence E. Open Source Licensing: Software Freedom and Intellectual Property Law. New Jersey. Prentice Hall Professional Technical Reference: 2005.