Multiple integrals extend the concept of integration to functions of several variables. They are used to calculate quantities such as area, volume, and mass in higher dimensions. The most common types are double and triple integrals, which allow for the integration of functions over two-dimensional and three-dimensional regions, respectively. In practical applications, multiple integrals are essential in fields like physics and engineering, where they help in solving problems involving multiple variables. For instance, they can be used to find the center of mass of a solid object or to compute the electric charge distributed over a surface.