Parabola (Locus Construction)

As you observe what happens when you modify the applet below, pay close attention to the relationship between point F, all points P, and line d.
Point F is called the "FOCUS" of this particular locus (set of points). Line d is called the "DIRECTRIX" of this locus. Fill in the blanks () to make a true statement. Hint: The terms "FOCUS" and "DIRECTRIX" are answers to at least one blank below. The locus of points shown in red is a ( ). Thus, a ( ) is a ( ), or set of ( ). Each point P on this ( ) is ( ) from a fixed point called the ( ) and a given line called the ( ).