The theory of several complex variables is a branch of mathematics that studies functions of multiple complex variables. It extends the concepts of complex analysis, which deals with functions of a single complex variable, to higher dimensions. This field explores properties such as holomorphic functions, which are complex functions that are differentiable in a neighborhood of every point in their domain. Key topics in this theory include complex manifolds, analytic continuation, and Cauchy-Riemann equations in higher dimensions. Applications of this theory can be found in various areas, including mathematical physics, algebraic geometry, and number theory, where it helps in understanding complex structures and their behaviors.