The Association of College and Research Libraries (ACRL) 5th Information Literacy Competency Standard for Higher Education:
There are various software products and website that assist you with determining if you paper has plagiarism issues.
Here are a few that have been in the news*:
Here are a few website that assist you in protecting your work*:
*Note the James E. Shepard Memorial Library does not endorse the external websites above, they are examples of resources that can help you understand plagiarism, copyright, and trademarks.