The English used in this article or section may not be easy for everybody to understand. (June 2021)
The point where the parabola reaches its maximum or minimum is called the "vertex." At this point the curvature of the parabola is greatest. This means the curve of the parabola is the tightest. The vertical line which passes through a parabola's vertex is called the "axis of symmetry". This is because the parabola looks the same on either side of that line.
Each parabola has a focal point. Any ray that enters the parabola and is parallel to the axis of symmetry will pass through this point after being reflected by the curve. Because of this fact, parabolas are important in devices such as satellite dishes, or magnifying mirrors. Parabolas are often used to approximate curves that are more difficult to model by themselves.