Parabola Graph.
Concepts behind Parabolas/Parabolic graphs
So to summarise, the Concepts behind Parabolas/Parabolic graphs are as such:

The distance from a given point Pn to the focus is always the same as th
e distance from Pn to a point Qn directly below.
The length of any line F - Pn - Qn is the same. This is similar to saying that a parabola is an ellipse, but with one focal point at infinity