Parabolas always have a lowest point (or a highest point, if the parabola is upside-down). This point, where the parabola changes direction, is called the "vertex". If the quadratic is written in the form y = a(x – h)2 + k, then the vertex is the point (h, k). This makes sense, if you think about it.
The vertex of a quadratic equation is either the minimum or maximum of the equation. If the parabola opens down, the vertex will be at the highest possible point, aka, the maximum highest point of the parabola. If the parabola opens up, it would be the lowest possible point, aka, the minimum lowest point on the parabola.
