Disclaimer: this is not legal advice, and can be inaccurate or wrong. Please consult an attorney in case of doubt.
Copyright and GNU Free Documentation License
Once an author makes his/her work public, such as in a journal article or a web document such as this wiki, by default the author becomes the copyright holder of this work from the date of first publication.
By putting some material in this wiki, each contributor should make sure that the copyright holder of this work, if any, agrees to distribute this work under the terms of the GNU Free Documentation License.
The purpose of the GNU Free Documentation License (GNU FDL) is to guarantee that a document is open and will remain open to modifications and further publications by anyone.
Frequently Asked Questions
Can I extract a paragraph from one of my papers and put it here?
Often the answer is no because many publishers ask you to sign an agreement that gives them exclusive rights to publish this work.
However if you did not publish your paper under such an agreement, and if yourself or the company that you represent and all your coauthors agree, you can place your material in this wiki. It means that you agree to distribute your work under the terms of the GNU FDL.
Can I extract a paragraph from someone else's paper and put it here?
You must ask the permission of the copyright holder. If there is no copyright on this work, i.e. this work is in the Public Domain, then you can publish it freely in this wiki.
Can I make a copy of a page of this wiki and put it in a book?
Yes, but you must respect the terms of the GNU FDL, so read it carefully.
Can I sell a paper version of the wiki?
Yes, but you must comply to the terms of the GNU FDL, which basically asks you to make the "source text" of your book available.