EndNote is software that allows you to keep track of your citations, organize them into folders, and create references and bibliographies in your papers.
You can:
EndNote is similar to Refworks and Zotero, but it allows you to produce bibliographies in a greater number of citation styles and allows greater customization. It is particularly popular in the sciences.
Unlike these web-based applications, EndNote is not free, and requires download and installation. You can download a 30-day trial version from the Endnote website, or buy it from the University of Illinois WebStore.
More details are available on this on the EndNote LibGuide.