Displacement reactions occur when one element replaces another in a compound. This type of reaction typically involves a more reactive element displacing a less reactive one. For example, when zinc is added to a solution of copper(II) sulfate, the zinc displaces the copper, resulting in the formation of zinc sulfate and copper metal. These reactions can be classified into two main types: single displacement and double displacement. In single displacement, one element takes the place of another in a compound, while in double displacement, two compounds exchange components. Displacement reactions are important in various applications, including metallurgy and chemical synthesis.