Zotero is a free citation manager that you can use to collect, manage, and produce citations for research sources. Zotero allows you to attach PDFs, notes, and images to your sources, 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.
To install, go to the Zotero site and choose the appropriate program. Click Download and follow the instructions.
If you have any problems, check the Zotero installation page.
You'll probably also want to download and install the Microsoft Word citation plugin (or the OpenOffice plugin if you're using OpenOffice). These allow you to easily cite items from your Zotero library in your papers.
Use Zotero on multiple computers with Zotero syncing. Library items and notes are synced through the Zotero servers (unlimited storage), while attachment syncing can use the Zotero servers or your own WebDAV service to sync files such as PDFs, images, or audio/video.
The first step to syncing your Zotero library is to create a Zotero account (which is also used for the Zotero Forums). Then, open Zotero's Sync preferences tab and enter your login information in the Zotero Sync Server section.
By default, Zotero will sync your data with the server whenever changes are made. To disable automatic syncing, uncheck the “Sync automatically” checkbox in this section.
In addition to automatic syncing, you can sync manually at any time by clicking the “Sync with Zotero Server” button on the right-hand side of the Zotero toolbar.