LEFT RIGHT DOUBLE ARROW

About this character

U+21D4, commonly called "if and only if" or left right double arrow, is a logical biconditional symbol. It asserts that two propositions share the same truth value: both true or both false. Rooted in logic, it formalizes equivalence and necessary-and-sufficient conditions. In programming and markup, it appears as an entity or in mathematical contexts, sometimes rendered as ⇔ or written as `<=>`. In typography and design, it offers a concise, symmetrical glyph for diagrams, notation, or layout symbols indicating mutual relationships or bidirectional linking. Its use extends to mathematical writing, formal logic, and occasionally technical documentation, where it clarifies logical equivalence.

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Character

Copy the literal character when you need the glyph itself:⇔