Focal point

A focal point may mean the same as focus. It may also mean:

In optics, a focal point is the point at which initially collimated rays of light meet after passing through a convex lens, or reflecting off of a concave mirror.
In mathematics, focal point means a critical point of a distance function.
In an antenna,
- The driven element, directly connected to the transmission line or source
- The parasitic element
In game theory, a focal point is an equilibrium more likely to be chosen by the players because it seems special, natural or relevant to them.