A precipitation reaction occurs when two soluble substances react in a solution to form an insoluble solid, known as a precipitate. This process typically involves the mixing of two ionic compounds, resulting in the formation of a new compound that cannot dissolve in the solvent. The precipitate can often be seen as a cloudy or colored substance that settles at the bottom of the container. These reactions are important in various fields, including chemistry, environmental science, and medicine. They are commonly used in laboratory settings to separate and identify different compounds. Precipitation reactions also play a role in natural processes, such as the formation of minerals in geology.