In organic chemistry, functional groups serve as the reactive sites in molecules, determining their chemical behavior and properties. These specific clusters of atoms impart distinctive characteristics to organic compounds, influencing factors such as solubility, boiling point, and reactivity. For example, the presence of a hydroxyl group (-OH) indicates alcohols, while carboxyl groups (-COOH) denote acids. Understanding functional groups is essential for predicting reactions and synthesizing new organic compounds, making them central to the study of organic chemistry and its various applications.