Typically the primary content of your document should be created by you and be your own original work. However, for research purposes or other reasons you may want to incorporate text, images, video or audio from another source. If you incorporate external materials, you need to make sure that the content is credited and available for reuse. This section contains a few guidelines for how to integrate external materials appropriately. This is called citation.
Citing your sources, also called referencing your sources (and sometimes called documenting your sources) is important for multiple reasons. First it lends credibility to your own writing by showing that you have used trustworthy sources and original research in an ethical way to inform your own ideas. It also helps readers find the sources of your information–your evidence for why you argue for a certain position or why you put forth a certain hypothesis.
Citation styles are standardized. In your high school or other previous English classes you may have learned about MLA (Modern Language Association) style citations. In technical writing the default standard is APA (American Psychological Association) style; however, different career fields use different citation standards. For example, in many of the sciences the CSE (Council of Science Editors) style is used.
Finally, remember anything written down, recorded, or posted to the web is under copyright. You cannot use something that is copyrighted without written permission from the owner.