Zotero's passive purpose (as opposed to active use for generating bibliographies) is in its capacity to serve as a comprehensive research library. When an entry is saved, Zotero will usually save the associated text information like the author name, the date of publication, publisher, etc. (metadata). For entries with incomplete metadata, you can easily fill it in in the metadata pane to the right of the library panel. In addition to metadata, Zotero users can enter searchable notes and tags to organize their research library. This function is useful when one is looking for citation support for components of larger research projects.