Q. Why do I need an in-text citation AND a reference for every source that I use in my research project?

Citations exist in large part to help your reader find and verify the information, ideas, images, etc. that you refer to in your writing or presentations. In-text citations and the full citations in your reference list work together to do this. So, while we usually think of "a citation" as singular, it's actually a two-part process. 
 

To completely cite a source, you must include both an in-text citation and a reference citation.
 

In-text citations 

An in-text citation (sometimes called a parenthetical citation) is placed in your writing immediately following a piece of information, quote, idea or image that came from another source. To keep your writing uncluttered and easy to read, an in-text citation includes just enough information for your reader to find the full citation in your list of references, at the end of the paper.  In many cases, it’s just author last name(s) and the publication year. 

Here's an example in-text citation from a peer-reviewed article:

How do you format your in-text citations?  That depends on the style guide that you are using! The library has style guides to help you create and correctly format your in-text citations.  Find your style guide linked in Writing@APUS: Citing Sources.  Look for: IN-TEXT CITATIONS | FORMAT.  Click that section to expand the details.
 

Reference citations 

At the end of your paper, you'll list all of the sources you referred to (and cited) as you wrote...this is the reference list, or works cited list.  For every parenthetical citation in your paper’s body text, there should be a corresponding full citation in the reference list.   

The full reference citation must include enough information to enable your readers to find the source themselves.  The exact format of each citation varies, depending upon the kind of source you're citing and the style guide you're using. Most full citations will include author name(s), title(s), and publication date, and many will call for pages, a DOI number or URL or publisher name. 

Here's the full reference citation that goes with the in-text citation we looked at above:

Sound like a lot?  No worries.  Watch this short video to learn how you can quickly generate a citation from the library's Everything search tool.  

The library has style guides to help you create and correctly format your reference citations from scratch, as well.  Find your style guide linked in Writing@APUS: Citing Sources.  Scroll down to the Citation Examples to find formatting tips and examples for various types of sources, from articles to videos.   
 

See also:

• Why do I need to cite my sources?
• What is plagiarism? How can I avoid it?
• How do I paraphrase or quote my sources correctly?