A discriminant is a quantity that gives valuable information about the solutions of an equation. In the case of a quadratic equation ax ² + bx + c = 0, the discriminant is given byD = b ² – 4ac. If D > 0, the roots of the equation are two different real numbers; if D = 0, the roots are real and equal; if D < 0, the roots are complex numbers. The concept of discriminant can also be applied in the case of polynomials, elliptic curves, and metrics.