Document Info palette — everything about the file in one place: PDF version, page sizes, title/author/dates, whether it is encrypted, the list of fonts (embedded or not) and the colour spaces used. Copyable, read-only.
Tags palette — the document's reading structure for screen readers, its language, whether viewers should show its title, and editable alternative text for the selected element.
Info palette — live cursor position and the size of what you selected.