These are typography's performers – letterforms designed to be seen from across the room, to stop the eye, to make a statement.
Film posters. Book covers. Headlines that demand notice.
Display fonts sacrifice readability for personality. They work best in small doses, at large sizes, where their distinctive character can shine without overwhelming the reader.
They can be quite decorative, or a special cut of a text face. Either way, they don’t work too well in small sizes (for instance, on a book page).