what is directrix, eccentricity, and focus

Let's assume a fixed point S on a plane and a fixed straight line L.

Now let assume there is a point P now if we move P in such a way that the ratio of perpendicular distance of P from the line L and distance from the point S if constant then we will get a conic section.

Then the line L is called directrix, the point S if called focus and the ratio is called eccentricity.