Mathematical exponents, also known as indices, are numbers that are used to indicate the power or exponent to which a quantity is to be raised. They are written as superscripts and are usually placed after a number or variable. For example, in the equation x2, the 2 is the exponent, indicating that x is to be multiplied by itself. Exponents are used to represent repeated multiplication of a number or variable, and can be used to simplify complex equations.