This document discusses catalytic cracking, which breaks down large hydrocarbon molecules into smaller, more useful molecules. It describes the different types of cracking processes and explains that catalytic cracking is most commonly used. Catalytic cracking uses lower temperatures and pressures than thermal cracking by using a catalyst. It provides details on the catalytic cracking process, including that it occurs in three basic functions: reaction, regeneration, and fractionation. It also describes the specific fluid catalytic cracking and moving bed catalytic cracking processes.