We're in the process of updating the documentation for Zotero 5.0. Some documentation may be outdated in the meantime. Thanks for your understanding.
This is a summary of past and planned Zotero and Zotero Website releases.
Zotero 1.0 - October 2006
Zotero 1.5 Beta: Introducing server sync - July 2008
With the release of Zotero 1.5 Beta, users gained the ability to sync their individual collections with the Zotero Server. Through server syncing, users can access and update their Zotero libraries from multiple locations. In order to support synchronization, this version also introduced data conflict resolution. Zotero 1.5 Beta also offered significant performance improvements over Zotero 1.0. Note that Zotero 1.5 never left beta. Instead, further development of Zotero 1.5 Beta resulted in Zotero 2.0 Beta.
Zotero Website: Account management - February 2009
This upgrade of the Zotero website made it possible for users to login at the Zotero website and see their collections online (this feature requires Zotero 2.0 Beta or later).
Zotero 2.0 Beta: Server sync with groups - May 2009
Zotero 2.0 Beta offers users the ability to share collections with others through the Zotero Server. Users can create collaborative groups and share notes along with their bibliographic metadata. Data is available at different access levels (e.g. read-only).
Zotero 2.0 - February 2010
Zotero-Internet Archive alliance – the “Zotero Commons” - September 2010
Users can drag and drop items into the “Zotero Commons” – a dedicated part of the Internet Archive’s servers.
Zotero Everywhere - January 2012
Standalone Zotero; plugins for Chrome and Safari; expanded website functionality and API; bookmarklet suitable for saving to Zotero from Internet Explorer and mobile devices.
Zotero Institutional Repository Integration - Under Development
Zotero Search API - Under Development