There are two versions of Zotero: Zotero for Firefox and Zotero Standalone.
Use Zotero for Firefox if:
Use Zotero Standalone if:
For Zotero Standalone, you will also need to install the Connectors to allow your browser to save items to your Zotero library.
Zotero will run on any operating system. It requires Mozilla Firefox 3.0 or greater. Installation only takes a few seconds. To install:
If you have any problems, check the Zotero installation page.
Connectors allow your web browser to save citations to your Zotero library.
Open Chrome or Safari and click the Zotero Connector link for that browser to install it.
Each browser has its own version of the Zotero connector, so if you use both Chrome and Safari you'll need to install both.
(Firefox does not require a connector to work with Zotero; it's built into Zotero for Firefox.)