Wikipedia's Five Pillars: Number 3
Wikipedia is free content that anyone can edit, use, modify, and distribute.
A crucial bit of this pillar is what it means to be 'free.'
The original content at Wikipedia, as contributed by people just like you—as opposed to copyrighted, non-free content that is used at Wikipedia under a claim of fair use, such as short quotations and some low resolution images—is automatically dually-licensed under highly free copyright licenses (CC BY-SA and the GFDL) that allow it to be taken, used, and modified by the public at large (even for commercial purposes), so long as suitable credit and a posting of the licenses accompanies its reuse.
An important takeaway is that most of the content added to Wikipedia must be original – written in one's own words. Reliable sources are cited to show that the information is verifiable, but the words and sentences are not copied except under limited fair use, such as including short quotations from sources, which must be marked as such using quote marks, and cited to the source of copying using an inline citation. Outside of such limited exception, copying and pasting copyrighted content into Wikipedia is illegal, as copyright infringement, and unethical as plagiarism. It is therefore crucial to understand the material you are adding, process it, rephrase it from a neutral perspective, and then add the content, while citing the corroborating source.
- Respect copyright laws, and do not plagiarize sources. Limited use of non-free content is allowed under a valid claim of fair use, but strive to find free alternatives to any media or content that you wish to add to Wikipedia.
- Since anyone can edit and modify Wikipedia articles, don't panic if you see your articles edited, or some of your contributions reverted. While you own under a free license the copyright of text you add to Wikipedia, if it is to sufficiently creative, you do not own the pages you added it to and have no right to control any page, which anyone can change or even seek to have deleted.