The "echo area" is used for displaying error messages for messages made with the `message' primitive, and for echoing keystrokes. It is not the same as the minibuffer, despite the fact that the minibuffer appears (when active) in the same place on the screen as the echo area.
(Info-goto-node "(elisp)The Echo Area").
val messagef : ('a, unit, string, unit) Core_kernel.format4 ‑> 'aval message_s : Core_kernel.Sexp.t ‑> unitval message_value : Value.t ‑> unit