What Is Delta in Math?

Delta refers to change in mathematical calculations. In some cases, this means a difference between two values, such as two points on a line. In other cases, it refers to the rate of change, such as in a derivative.

Although it usually refers to change, delta itself is a Greek letter that can also be used as a variable in equations. Typically, if used to signify change, it is followed by another variable, such as ?X.