When you quote or paraphrase the idea of another person in your research paper, presentation, or speech, you need to use proper citation for the source in a bibliography and references.

• gives credit to the author
• enables the reader to locate the resource you cited
• lends credibility to your work, especially when you use authoritative sources

Using other people's ideas and not giving them credit via providing proper references is plagiarism which is both an honor code violation and a federal crime.