Copyright:
Copyright is the exclusive legal right, given to an originator or an assignee to print ,publish, perform, film, record literary, artistic, or musical material, and to authorize others to do the same. Could be thought of as a patent on literary materials.
Plagiarism:
Plagiarism is the use of someone’s idea as if it was your own.
Fair Use:
Fair use is the doctrine that brief excerpts of copyrighted material can be quoted, without penalty, for purposes of reporting, teaching , and research. If you use copyrighted material in research or as a teaching tool just insure to give due credit by citing the source of the information. To do this you can use a citation manual or one of many websites that will cite the source for you my favorite one of these is citationmachine.com
Resources:
https://www.copyright.gov/fair-use/more-info.html
http://www.plagiarism.org
https://www.copyright.gov/help/faq/
https://owl.english.purdue.edu/owl/resource/560/01/