A hoax is a deliberate attempt to deceive or trick an audience into believing or accepting that something is real, when the hoaxer (the person or group creating the hoax) knows it is false.

In the instance of a hoax, an object or event is not what it appears or is claimed to be; for example, "red mercury", which was widely offered by 90th of XX century after the USSR collapse by different sorts of criminals.
Usage of a hoax varies from harmless joke till huge system of political ideology like created by Bolsheviks on the territory of FSU and some other countries (North Korea). Some governments have been known to perpetrate hoaxes to assist them with unpopular aims such as going to war such as Russia-Georgia war of 2008 when Russia through mass-media well prepared public opinion on the planned military invasion to Georgia and occupation about 20% of its territory.

A hoax differs from a magic trick in that the audience is unaware of being deceived, whereas in watching a magician perform an illusion the audience expects to be tricked.