Plagiarism is using someone else's work or ideas without full and clear acknowledgment.
Plagiarism is a violation of academic integrity with potential academic penalties.
Always give credit where it is due. You would like others to acknowledge your work and original ideas, so it is only right that when you use someone elses' words or ideas, you acknowledge them through proper citation. This means that not only exact quotations must be cited, but also paraphrases and summaries of other's ideas. You must also cite images, music files, etc.--anything that you did not create. If you did not make it, you must cite it! Proper citation includes in-text citations, as well as citing works in your bibliography.
Know the Academic Integrity Policy of Duquesne University as well as the policy and procedures of the specific School that offers your course.