A citation is a reference to the source of an idea, information or image.
Any words, ideas or images that you do not create yourself must be given credit if you use them in your work.
Citing information sources lets the audience know the origins of your information (in case they would like to locate the original), gives credit to the originator (credit where credit is due) and helps you to avoid plagiarism.
For more complete information about citation styles, please see the LibGuides for MLA, APA, or Chicago styles.