Copyright
Copyright laws are what protect the work of authors or creators of work that own the rights to the work. If you are not the author, creator or owner of a piece of work you can not re-write, re-publish, or claim ownership in any way for that work. Using someone else's work without permission is classes as plagiarism under the copyright law. However work can used to reference from by saying where the content was taken from for example by using the hazard reference system to write a quote in an essay. If the copyright law is broken there could be possible consequences if the creator finds out about the infringement.
