When creating a reference, the final step lets you add tags. Tags are hidden markers you can use to group references into specific categories. For instance, you could add the tag "Cryptozoology" to any reference you use in your Cryptozoology class.
Once you've added a tag to a reference, you can search for it in the References Module or Reference Library. Type the tag name to search, or type "#" followed by the tag to search specifically by tag (e.g., #cryptozoology).
You can also add tags to existing references by editing them.