In Metaphysics, 'dualism' designates the position that there is more than just matter in the Universe. There are two types of dualist theories:
Substance Dualism is the most common form of dualism and maintains there are two distinct substances in the Universe: matter and minds. Both substances are elemintal substances (or 'stuffs') so that neither can be reduced to the other. According to this theory we are minds (or souls) inside bodies.
Property Dualism holds that minds or mental events are properties which emerge from a particular organization of matter.