# Partial Differential Equations

Partial differential equations (PDEs) are equations that involve an unknown function and its partial derivatives. PDEs are widely used in mathematics, physics, engineering, and other fields to describe various phenomena, such as heat conduction, fluid flow, or wave propagation. They are a generalization of ordinary differential equations (ODEs), which involve only ordinary derivatives of the unknown function.

There are many types of PDEs, including linear and nonlinear, homogeneous and inhomogeneous, and elliptic, parabolic, or hyperbolic, each with its own unique characteristics and solution techniques. Some well-known PDEs include the Laplace equation, the wave equation, and the heat equation.

Solving PDEs can be challenging, and often involves techniques such as separation of variables, Fourier series, and integral transforms. Numerical methods, such as finite difference and finite element methods, are also used to approximate solutions to PDEs when analytical solutions are not possible.