Opinions vary among magicians on how to categorize a given effect, but a number of categories have been developed. Magicians may pull a rabbit from an empty hat, make something seem to disappear, or transform a red silk handkerchief into a white handkerchief. Magicians may also destroy something, like cutting a rope, and then “restore” it, make something appear to move from one place to another, or they may escape from a restraining device. Other illusions include making something appear to defy gravity, making a solid object appear to pass through another object, or appearing to predict the choice of a spectator. Many magical routines use combinations of effects.