A double chin is a fatty deposit located on the fleshy area just below the chin. This fatty deposit causes the appearance of having two chins. There are two causes of the double chin: obesity and genetics.
There may be solutions to the double chin. Proper diet and exercise will cure this in the case of obesity. Please consult your physician for more information. In the case of genetics, you are probably stuck with your double chin but you may try localized exercises focusing on the neck area.