Zotero saves references from most library databases and web pages with one click.
When Zotero detects that you're looking at a book or article on a catalog, database, or website like Amazon.com, you'll see a book or page icon appear in or near the address bar of your browser. Just click the icon and Zotero will automatically save the citation. Zotero will import your citation in the the last folder you had open.
Make sure Zotero is open before you begin to save citations, otherwise you will get an error message and the option to save it to your online account.
Tips for organizing your citations: