U+21C6 "⇆" Leftwards Arrow over Rightwards Arrow Unicode Character

U+21C6 "⇆" Leftwards Arrow over Rightwards Arrow is a specialized arrow symbol that combines a leftward and a rightward arrow stacked vertically, representing bidirectional flow, exchange, or alternation between two directions. Often used in mathematical notation, chemistry for equilibrium reactions, or user interface design to indicate a toggle or swap action, this character belongs to the Arrows block of Unicode and is formally named "Leftwards Arrow over Rightwards Arrow." Its visual design places the left-pointing arrow above the right-pointing arrow, distinguishing it from similar bidirectional symbols like the left-right arrow.