What is citing and citations?
Citations can be a quotation from or reference to a book, paper, or author, especially in a scholarly work - OED Online
Citing a source means that you show, within the body of your text, that you took words, ideas, figures, images, etc. from another place - MIT Libraries
Citations are a short way to uniquely identify a published work (e.g. book, article, chapter, web site). They are found in bibliographies and reference lists and are also collected in article and book databases - MIT Libraries
Why cite sources? (From Arizona State University)
Citations credit the author of the original work who provided you with the information or idea
Citations allow your audience to identify and find the source material in order to learn more about your topic
Citations give your paper more credibility because it shows you're supporting your arguments with high-quality sources
Citations help you avoid plagiarism & demonstrate your integrity as a responsible researcher and participant in your field of study