The keto-enol tautomerism refers to the chemical equilibrium between two forms of a compound: the keto form, which contains a carbonyl group (C=O), and the enol form, which has a hydroxyl group (–OH) attached to a carbon-carbon double bond (C=C). This transformation is significant in organic chemistry as it can influence the reactivity and properties of molecules. In many cases, the keto form is more stable than the enol form, but certain conditions, such as the presence of acids or bases, can favor the enol form. This concept is important in various fields, including biochemistry and pharmaceutical chemistry, where the stability and reactivity of compounds can affect biological activity and drug design.