 At most points, the tangent touches the curve without crossing it (though it may, when continued, cross the curve at other places away from the point of tangent).A point where the tangent (at this point) crosses the curve is called an "inflection point".Circles, parabolas, hyperbolas and ellipses do not have any inflection point, but more complicated curves do have, like the graph of a cubic function, which has exactly one inflection point, or a sinusoid, which has two inflection points per each period of the sine.