Thermal cracking: Heating of hydrocarbons to very high temperatures, usually above 450ý C. Thermal cracking is no longer widely used, except in:

Visbreaking: Thermal cracking of viscous crude residues to make fuel oil, and in:

Delayed Coking: Thermal cracking of atmospheric/vacuum residues to make electrode grade coke.

Catalytic cracking: Cracking using catalysts to enhance molecule breaking, particularly in the production of high octane gasoline.

Hydrocracking: While thermal and catalytic cracking produce shorter hydrocarbon molecules largely by disposing of the excess carbon atoms, hydrocracking inserts hydrogen atoms to achieve the same effect.

Steam cracking: A petrochemical process which produces olefins, particularly ethylene, and, in some cases, aromatics. Similar to thermal cracking

Co-Cracking: A petrochemical process in which the c4 stream from an ethylene plant is recycled into the feedstock.