Spontaneous human combustion (SHC) refers to the belief that the human boy sometimes burns without an external source of ignition. There is much speculation and controversy regarding SHC, for it is not a proven natural phenomenon. Many theories and hypotheses have attempted to explain how SHC might occur, but those which rely on current scientific understanding say that instances mistaken for spontaneous combustion actually required a source of ignition. One such hypothesis is the "wick effect", in which the clothing of the victim soaks up melted human fat and acts like the wick of a candle. Another possibility is that the clothing is caused to burn by a discharge of static electricity. The likelihood that truly spontaneous human combustion actually takes place is remote, due to the presence of water and the lack of highly flammable compounds and oxygen in the human body.