A parabola is the graph of a quadratic function. Each parabola has a **line of symmetry**. Also known as the **axis of symmetry**, this line divides the parabola into mirror images. The line of symmetry is always a vertical line of the form *x* = *n*, where *n* is a real number.

This tutorial focuses on how to identify the line of symmetry. Learn how to use either a graph or an equation to find this line.