This book discusses recent research and developments related to characterization and utilization of petroleum-derived asphaltenes. Chapters cover computer simulation of physical density and thermal properties, precise measurements of molecular weights of asphaltene, estimation of structural parameter distribution, characterization of refractory sulfur compounds, hydrotreatment, cracking, visbreaking, and coking reactivities. In petroleum industries, heavy petroleum residue due to enhanced oil recovery is becoming a serious problem. Heavy oils cause problems during oil production and refining processes. Increased viscosities reduce, or even stop, the flow of oil during oil production. Meanwhile in refining processes, their undesired precipitation, high tendency to form coke, and catalyst deactivation and poisoning should be involved.