Choose Zotero for Firefox if:
Zotero for Firefox runs as a plugin for the Firefox web browser, not as a separate program. The same version of Zotero for Firefox works on any computer that runs Firefox; there are no separate Windows and Mac versions.
Choose Zotero Standalone if:
Zotero Standalone (unlike Zotero for Firefox) runs as a separate program instead of part of your web browser. It works with Firefox, Chrome and Safari. Download and install Zotero Standalone just as you would any other program. You will also need to install the Connectors to allow your browser to save items to your Zotero library. Trouble installing Zotero? Visit this page for help.
Word processor plugins allow you to insert citations and bibliographies directly into your documents. Installing them is optional but highly recommended. (If you're using Zotero Standalone, you don't need to install Word toolbars; they are included with Zotero Standalone.)
Go to the Word Processor Plugins page. Choose the most recent version of the plugins if you're installing Zotero for the first time.
Word for Mac/Windows users: