U+21C4 "⇄" Rightwards Arrow over Leftwards Arrow Unicode Character

U+21C4 "⇄" Rightwards Arrow over Leftwards Arrow is a typographic symbol that depicts two horizontal arrows pointing in opposite directions, with the rightward arrow placed above the leftward arrow. It is commonly used in mathematics, chemistry, and formal notation to represent a reversible reaction, a bidirectional exchange, or a cyclical swapping of elements between two states or components. In computing and user interface design, this character can also signify a data transfer or synchronization process that flows in both directions, making it a concise visual shorthand for mutual interaction or equilibrium.