Halogenation is a chemical reaction that involves the addition of halogen atoms, such as chlorine, bromine, fluorine, or iodine, to a molecule. This process typically occurs with organic compounds, particularly alkenes and alkanes, and can result in the formation of haloalkanes or haloarenes. Halogenation can be initiated through various methods, including free radical mechanisms or electrophilic addition. The reaction can significantly alter the properties of the original compound, often increasing its reactivity and changing its physical characteristics. Halogenated compounds are widely used in various applications, including solvents, pesticides, and pharmaceuticals, making halogenation an important process in organic chemistry.