Detecting whether a point is in a box.

Hello

I am trying to write a query to find all points that fall within a
given box. However, I cannot seem to find the functionality for
determining whether a point is within a box.

e.g.  select box '((0,0),(1,1))' @> point '(0.5,0.5)';

operator does not exist: box @> point

Is this operator for circles only? Is there a similar operator for
boxes? I have not been able to find it in the documentation.

Any help would be much appreciated
H