Click and drag in the main window to rotate the object. Click once to stop the rotation.
Select a different object in the drop-down menu (the default is a Tetrahedron). You may display the internal IDs of the points where struts are joined with cords ("nodes") and the tensions in the structure (negative values indicate compression).
Click and drag in the sliders to change the length of the cord (the red rubber bands) between the corners of the figure in relation to the full length, to change the damping factor of the simulation (a kind of internal friction, determining how 'springy' the figure behaves), and to change the scale of the figure (i.e. to make it bigger or smaller).
The check boxes at the bottom turn relaxation on or off (i.e. the simulation of the forces shaping the tensegrity structure) and randomly pluck the struts (i.e. pull the black sticks and then let them return to their original position).
Tensegrity structures are objects in which solid struts are linked by cords. The tension of the cords is taken up by struts opposing the compressional force exerted on them. The structure takes on a shape in which all the forces are balanced. In the applet above, some structures which are based on regular polyhedra can be selected. Moving the "Relative cord length" slider to the right reveals the polyhedron, because in this position the end points of the struts are pulled together in the vertices of the structure.
The artist Kenneth Snelson first elaborated on the concept at the end of the 1940's. The term Tensegrity was coined by the architect Buckminster Fuller.
For an overview on the concept and applications of tensegrity, see the Wikipedia article "Tensegrity".