U+21C5 "⇅" Upwards Arrow Leftwards of Downwards Arrow Unicode Character

U+21C5 "⇅" Upwards Arrow Leftwards of Downwards Arrow is a special symbol that combines two vertical arrows into a single glyph, where an upward-pointing arrow is positioned to the left of a downward-pointing arrow. This character is often used in mathematical notation, technical diagrams, and certain data visualizations to denote a bidirectional vertical relationship, such as a two-way flow, a coupling, or an alternating motion between two states. Its unique arrangement visually suggests both an ascent and a descent occurring in parallel or sequence, making it useful for representing concepts like up and down cycles, paired opposing forces, or coordinated vertical movement in fields such as physics, engineering, or user interface design.