Asphalt (ˈæs.fɒlt (help·info)) is a sticky, black an highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits sometimes termed asphaltum. It is most commonly modeled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase (though there is some disagreement amongst chemists regarding its structure). In U.S. terminology, asphalt (or asphalt cement) is the carefully refined residue from the distillation process of selected crude oils. Outside North America, the product is called bitumen.