Whenever you do research to write a paper or create a project, it is essential that you document the sources that you used. When you cite your sources, you lend authority and credibility to your work by providing evidence for your research and by helping your reader to determine how you drew upon the work of others to support your own original argument and ideas. You also avoid plagiarism by giving credit to the authors whose work informed your own.
You must include a citation if you quote directly from a source, but also if you paraphrase, summarize, or otherwise incorporate another author's opinions or ideas. It is also important that you cite the sources in which you found facts, information, data, and visuals (images, charts, or graphs) that you used in your work.