∆

∆ may refer to one of the following:
 * Triangle (∆), one of the basic shapes in geometry
 * Delta (letter) (∆), a Greek letter also used in mathematics and computer science
 * alt-J (∆), a British indie band
 * Laplace operator (∆), a differential operator
 * Increment operator (∆), character U+2206
 * Symmetric difference, in mathematics, the set of elements which are in either of two sets and not in their intersection