As implied by the name, vegetable oil is obtained by expressing oil (compression and extraction) that is contained in plants. Therefore, all plants that contain oil can be used as the ingredients of vegetable oil. Even so, it is difficult and inefficient to express oil from plants that only contain a small amount of oil. Therefore, plants which contain a large amount of oil are selected and used as the ingredients of vegetable oil.

Depending on their form, agricultural products used as the ingredients for vegetable oil are categorized as shown below in Table 1.

Table 1: Categories by form of ingredients for vegetable oil