A license tells the recipient what he is allowed to do with it. The Creative Commons license is a way to allow spread of work with some limitations, that can be defined by the author. If you write, paint or records something, you automatically own it and others are not permitted to copy, download or re-distribute it. If you put a painting, book, album or other you have created under a certain license, you can actively allow people to re-use or distribute your work. For example to print it in a magazine, submit it to their blog, burn it on a CD and sell it or even remix or manipulate your works.
If you now ask, why you should allow people to do that, there is a simple answer: It could be of good use. Let’s pretend you’ve made a great banner against animal abuse and it’s made public domain, nobody else could use it. Putting it under a creative commons license, people can create banners for their local events for it, or just print it to spread the word.
There also is a financial side in this. The Nine Inch Nails submit music as creative commons licensed and they are still having financial success, because you can gain a lot of audience, giving out things for free and offering something extra they can buy. NIN released the albums under following license: http://creativecommons.org/licenses/by-nc-sa/3.0/us/
- to share the work with others
- to remix it and produce own work with it
However, you may not:
- claim the full copyright, the songs are still by NIN or the parts you use
- make profit with it and not with derivates from it
- use it without credits to NIN
If you have something, that you would like to share, maybe an essay, maybe a photography you think is important, you can have a look at the creative commons website and find the license, that is right for you.
A quick overview can be found here: http://creativecommons.org/licenses/
Here a localised page in many languages: http://creativecommons.org/choose/