Created by the Center for History and New Media at George Mason University, Zotero is a free citation management tool that helps you organize, collect, and share your research.
Zotero allows you to attach PDFs, notes and images to your citations, organize them into collections for different projects, and create bibliographies.
It automatically updates itself periodically to work with new online sources and new bibliographic styles.
There are many other tools for citation management out there besides Zotero. Which one you use is up to you. They all do similar things, just in different ways. Check out these other great tools and get help at University of Nebraska-Lincoln Libraries: