Integral equations are mathematical equations in which an unknown function appears under an integral sign. They relate a function to its integral, often expressing physical phenomena such as heat conduction or fluid flow. Integral equations can be classified into two main types: Fredholm and Volterra equations, depending on the limits of integration and the nature of the unknown function. Solving integral equations often involves techniques similar to those used in solving differential equations. Methods such as Laplace transforms, Fourier transforms, and numerical approaches are commonly employed. These equations play a crucial role in various fields, including physics, engineering, and economics, where they model complex systems and processes.