Petroleum is a substance that occurs naturally in a yellowish-black form. It is found in a liquid form in the geological formations underneath the Earth's surface. It includes all solid, liquid and gaseous hydrocarbons as well as crude oil. Under surface temperature and pressure, pentane and other heavier hydrocarbons exist in solid and liquid forms. Under the same conditions the lighter hydrocarbons such as methane, propane, ethane and butane exist in gaseous forms. Petroleum is a fossil fuel that is obtained from the ancient fossilized organic materials such as zooplankton and algae. Petroleum formation is the result of the hydrocarbon pyrolysis at high temperature and pressure in a number of endothermic reactions. Alkenes, asphalt, lubricants, aromatic petrochemicals and paraffin wax are a few of the useful products derived from the mixture of hydrocarbon and non-hydrocarbons. The excessive use of petroleum as a fuel is a threat to the environment. It is a major cause of global warming and ocean acidification. This book contains some path-breaking studies in the field of petroleum science and technology. Most of the topics introduced herein cover new techniques and the applications of this field. It will help the readers in keeping pace with the rapid changes in this area.