A citation, also known as a reference, is a direct, specific description of a particular work. Each citation usually includes the date of creation or publication, the creator's name, and the title of the work.
Why use citations?
It protects you against accidental plagiarism. When you give creators credit for their work through citation, you are not plagiarizing their ideas.
It creates authority for your ideas. If you use the work of experts to support your ideas, your arguments are stronger.
It gives your reader or audience an opportunity to learn more.
How do I use citations?
There are many different citation styles. Most citations have an in-text citation in the body of your writing and a list at the end of the document of all the citations. The most common for the scientific disciplines is APA. Social sciences and the humanities may use the Chicago Style or MLA. Your professor will tell you which to use.
The Georgia Tech Library recommends the Purdue OWL online guide to citation styles. It is extensive and free for anyone to use. It can be found at Purdue OWL.