Zotero Groups allow you to share references with other Zotero users online. It's a great way to work on collaborative research projects.
First, set up Zotero sync and synchronize your library. Then see the instructions below for starting a new group or joining a group.
To join an existing Zotero library, search for it on Zotero.org or be invited by the group’s owner. You must log in to the zotero.org website to create or join a group, but you do not need to log in to simply view a group's public library.
After you've created or joined at least one group, you'll have have two sections in your Zotero collections pane: "My Library" and "Group Libraries."
Personal and group libraries are entirely separate, and changes made to items in one library do not affect the other. You can drag items back and forth libraries to copy items.