Ketones are a class of organic chemical compounds characterized by a carbonyl group ($\text{C=O}$) positioned between two other carbon-containing groups ($\text{R}-\text{C}(=\text{O})-\text{R}'$). In biological systems, they are primarily metabolic intermediates. They are notably formed during conditions of extended fasting or periods of high lipid catabolism, a process known as ketogenesis. These resulting molecules serve as alternative energy substrates, providing an efficient fuel source for various tissues, particularly those that are sensitive to fluctuations in glucose levels. Chemically, they are integral to biochemistry, forming the basis for various reactions and playing a role in maintaining metabolic homeostasis.