Biodiesel is a diesel blend stock that is derived from renewable (non-fossil) sources such as vegetable or animal oils.

Some minimal use of biodiesel is mandated in many markets.

The term biodiesel typically refers to a product made through esterification of vegetable oil feedstocks, resulting in esters such as FAME, RME, etc. These types of biodiesels contain oxygen so their use in finished diesel blends is often limited by maximum content specifications. They are susceptible to microbial contamination, and have poor cold flow properties.

There are more advanced processes based on hydrotreating vegetable oils, which produces diesel with properties very similar to fossil sources of diesel and with very high cetane levels. This type of bio derived diesel is typically referred to as renewable diesel or hydrotreated vegetable oil (HVO)