Tooltip
（重定向自Tooltips）
The tooltip or infotip or a hint is a common graphical user interface element. It is used in conjunction with a cursor, usually a pointer. The user hovers the pointer over an item, without clicking it, and a tooltip may appear—a small "hover box" with information about the item being hovered over. Tooltips do not usually appear on mobile operating systems, because there is no cursor (though tooltips may be displayed when using a mouse).