This document discusses the concepts of chirality and prochirality. Chirality refers to molecules that have mirror images that are not superimposable, often involving a carbon bonded to four different groups. Prochirality refers to molecules that can be converted from achiral to chiral in a single step. Chirality and prochirality are important concepts in stereochemistry and biochemistry, as most biologically relevant molecules like carbohydrates, proteins, and nucleic acids are chiral.