Copyright
According to http://www.copyright.com copyright is a form of protection grounded by the laws of the United States to the authors of "original works of authorship," including literary, dramatic, musical, artistic, and certain other intellectual works. The protection covers both the published and unpublished works.
Plagiarism
Plagiarism is the practice of taking someone else's work or ideas and passing them off as one's own. When using someone else's work, you must give credit to the original source. Since there are different formats to cite a source along with various types of sources, it is important to know different websites to assist you. Three great websites that can assist you in citing work are: http://plagiarism.org , https://owl.english.purdue.edu, and www.wikihow.com/Cite-Sources.
Fair Use
Fair use is the legal concept that allows the reproduction of copyrighted material for certain purposes without obtaining permission and without paying a fee or a royalty. Purposes permitting the application of fair use generally include review, news reporting, teaching and scholarly research.
References: http://en.wikipedia.org