What are tags?
Tags are a flexible way to organize books you finished, want to read, loved, or hated.
You can tag books from all of your libraries, and they'll appear under Shelf > Tags. You can also rename them, delete them, or add as many tags as you'd like.
Tags are specific to each device and don't sync between devices right now, but we're planning to add tag syncing to Libby in the future.