Stock items represent commonly-used menu or toolbar items such as "Open" or "Exit". Each stock item is identified by a stock ID; stock IDs are just strings, but properties such as Gtk.Stock.Open are provided to avoid typing mistakes in the strings. Applications can register their own stock items in addition to those built-in to Gtk#.

Each stock ID can be associated with a Gtk.StockItem, which contains the user-visible label, keyboard accelerator, and translation domain of the menu or toolbar item; and/or with an icon stored in a Gtk.IconFactory. See Gtk.IconFactory for more information on stock icons. The connection between a Gtk.StockItem and stock icons is purely conventional (by virtue of using the same stock ID); it is possible to register a stock item but no icon, and vice versa.