Citation Managers are tools to help you keep track of your citations as you research and to create/format your citations and bibliography. For example, Zotero allows you to keep citations, full text articles, and other research resources organized in one place. You can also use these tools to format your bibliographies and the notes/citations in your papers according to the appropriate style (APA, MLA, Chicago, etc.).
Watch this video to learn more about Zotero