Levitation (from Latin levare, to raise) is the process by which an object is suspended against gravity, in a stable position, by a force without physical contact.
It is also a popular conjuring trick, such as apparently raising a human being without any physical aid. The illusion can be produced by clever mechanics, lighting arrangements or other means.
On earth all that is required for levitation is a force vertically upwards equal to the object's weight. This can be achieved through many different means, for example magnetic, electrostatic (i.e. electrically charged objects) or aerodynamic forces. By means of magnetic levitation even small live animals have been levitated.
Scientists have discovered a way of levitating ultra small objects by manipulating the so-called Casimir force, which normally causes objects to stick together by quantum force. This practice however, is currently only possible for micro-objects.
Aerodynamic levitation is commonly seen in air hockey where jets of gas from the table push upwards against the puck. Levitating objects may also force air downwards e.g. Helicopters, VTOL aircraft, and hovercraft. A sphere can be stably levitated in a stream of air without any type of control system, if conditions are right. This was merchandised as a toy, circa 1960.
* Schiller, Christoph (2007). Motion Mountain: The Free Physics Textbook. esp. the section on levitation in the chapter on electromagnetism.