Examples of CopyLeft

CopyLeft licenses ensure all future derivatives of the product to include the original CopyLeft word for word, thus keeping the product free whenever it changes.

The first form of CopyLeft licensing is called the GNU General Public License (GPL):

http://fluidmedia.ws/blog/media/blogs/a/gnu-linux.jpg

• Originally made for the infamous Linux OS (logos of GNU and Linux above)
• It is now widely used to CopyLeft software such as Mozilla Firefox, Java, and OpenOffice
• http://sourceforge.net/ contains a large variety of computer software that has been CopyLefted to constitute as free software 

The second form of CopyLeft Licensing is the Creative Commons ShareALike License:

• This form of CopyLeft is more prominent in the art community
• It can be applied to documents to make the open content for the public
• eg. http://www.wikipedia.org/ articles are free under ShareALike
• Open content can be exposed to the 4 R's which are similar to the 4 freedoms (via http://opencontent.org/):
1. Reuse – Use the work verbatim, just exactly as you found it
2. Revise – Alter or transform the work so that it better meets your needs
3. Remix – Combine the (verbatim or altered) work with other works to better meet your needs
4. Redistribute – Share the verbatim work, the reworked work, or the remixed work with others

CopyLeft in the music Industry:

Cover of Girl Talk's newest album 'All Day'

Girl Talk is an artist who samples audio tracks from popular songs as well as vocal tracks and remixes the two together to form new songs under the 'fair usage' rights of CopyLeft.

• He is able to distribute his songs non-commercially via ShareALike licensing.
• All his albums are available free of charge (with the option to donate)
• All songs and albums have the proper credits to each original artist