This book provides readers with introductory information on oil and natural gas industry and engineering. It was written primarily for students at the university level, whose contribution will be crucial to the energy industry for continuing ability to supply the world. This book also is an essential reference for non-engineering petroleum industry technical and non-technical professionals. It addresses several petroleum and natural gas engineering issues including principals of oil and gas generation, exploration techniques, reserves estimation, field development, production optimization, reservoir management, the aspects of well drilling and completing, oil refining, oil and gas transportation, oil spill, and basic oil and gas economics. Additionally, the essential units and conversion factors were discussed in a simplified manner.