To understand petroleum products it is necessary to understand their composition as well as the processes that are used in their production. The purpose of this chapter is to describe the main products produced at a refinery and the key properties that define their quality. The most profitable products that a refinery makes are gasoline and diesel, and the lowest value products are petroleum gases and coke. Three wide fractions referred to as light distillates, middle distillates, and heavy ends correspond roughly to the transportation fuels gasoline, jet fuel/diesel, and residual fuel oils. Eight narrow fractions and about two dozen categories of finished product are commonly applied with a dizzying variety of names and specifications. Quality parameters depend upon application and standards, and so basic information regarding how refined products are used and regulated is needed for context. This chapter is loaded with terminology and definitions, and a good strategy might be to read in short segments or to return to as needed.