∆
∆ may refer to:

Triangle (∆), one of the basic shapes in geometry. Many different mathematical equations include the use of the triangle.
Delta (letter) (Δ), a Greek letter also used in mathematics and computer science
ᐃ, a letter of Canadian Aboriginal Syllabics
Delta baryon (Δ), one of several Baryons consisting of up and down quarks.
alt-J (Δ), a British indie band
Laplace operator (Δ), a differential operator
Increment operator (∆)
Symmetric difference, in mathematics, the set of elements which are in either of two sets and not in their intersection