Zotero's Groups feature allows you to share references with other Zotero users online. It's a practical way to work on collaborative research projects.
You now have two sections in your Zotero collections pane: My Library and Group Libraries.
Personal and group libraries are entirely separate; changes made to items in one library do not affect the other. You can drag items back and forth libraries to copy items.
Search for existing public groups or create a new group. Groups may be public (searchable, and anyone can join) or private (users can only join if invited).