"APA" stands for American Psychological Association, which is a professional organization for the field of psychology. APA writes and publishes its own publication manual, which describes in detail all of the rules and regulations regarding APA Style. APA Style involves rules about not only citation and referencing, but also writing and formatting. APA Style is widely used across disciplines, particularly in the sciences and social sciences. These style rules are intended to make scholarly writing more uniform so that it is more widely accessible and understandable.
Image taken from http://www.apastyle.org/index.aspx.
The APA Style Blog publishes weekly articles about various aspects of APA Style. It is an official supplement to the publication manual, written and maintained by experts on APA Style. If you have a question about APA and you can't find the answer in the publication manual, try searching the blog's website for answers.
Citation is necessary because scholars (and other honest people) want to share ideas without stealing them.
When you create a research paper or presentation, it is (or should be) a combination of your original thoughts and the knowledge you have gained from the thoughts of others.
Citation is a way of giving credit to those whose ideas made your final product possible.
The Greenspring and Owings Mills campus libraries as well as the Learning Commons have multiple copies of this publication manual, both in the reference section and available for checkout.