There are two major reasons for citing sources. The first is to give credit to the author(s) or originator(s) of a work and to avoid plagiarism. Plagiarism is taken very seriously. The penalties for plagiarism can vary from a zero on an assignment, a failing grade in a course, disciplinary probation, expulsion or suspension. The second reason for citing sources is so the reader can locate the source cited, if s/he desires.
There are two places where you will cite your sources; within the text of your document and at the end, in your References or your Works Cited list.