This chapter is an introduction to the most important topics regarding the crude oil market. Several data and facts of the market are briefly presented. An outstanding feature of crude oil at the core of public debates is its character as a fossil and non-renewable fuel. The chapter enlightens what this means in economic terms and how it is connected to the investigation at hand. As another issue, recent research on the oil market has, to a great part, focused on the driving forces of the oil price. In particular, our interest is in the question of whether economic fundamentals are the only factors influencing the price or whether speculation may also be effective. Finally, the role of OPEC and its potential power to impact on the oil market is considered.