Bookshelves in GoodReads are the way you can tag a group of books.
Everyone starts off with 3 shelves: Read, To Read, and Want To Read.
Tagging
Examples of creative bookshelf names, e.g., Bettie, Audrey Cabray,
Tagging as a 21st century skill filtering / curating
Limitations of GoodReads:
-- can't add a description to a bookshelf
HOW TO COMBINE shelves -- do an intersection.... ?