What does the term "cracking" mean in chemistry?

Cracking is the chemical process of breaking down large hydrocarbon molecules into useful products. For example, cracking breaks down the hydrocarbon molecules of decane into propene and heptane.

Cracking is used primarily to distill crude oil and petroleum. The two main types of cracking are steam cracking and catalytic cracking. The steam cracking process uses reactant gases and liquids to distill oil. Catalytic cracking uses vaporized gas oil to produce fuel and hydrocarbon gases. A third and lesser-known process is called hydrocracking. This process is used in the production of alkalenes for biofuels. Hydrocarbon molecules are also made into useful products through structural manipulation processes, such as isomerization and reforming.