Other curves: conics
The hyperbola,
This display illustrates a property of all hyperbolas. Any hyperbola has two points called the foci - points F1 and F2 in the diagram. Any point on the hyperbola has the property that the difference of its distances from F1 and F2 is always the same, and equal to the length AB. Move point F1 or F2 to see this. You can change the distance AB too. (Note that AB has to be less than the distance between the foci; otherwise you get another conic curve altogether.)

Conic curves The hyperbola is an example of a conic curve. This means that you can make a slice (shown in green) through a cone that creates a hyperbolic cross-section (shown in red).