This document presents information on partial differential equations (PDEs) including non-linear PDEs and their applications. It discusses standard types of non-linear PDEs like Clairaut's form where the PDE is formed as z=px+qy+f(p,q). It also provides examples of PDE applications in fields like engineering, physics, finance, fluid dynamics and heat transfer. Some limitations of PDEs are also outlined such as complexity, boundary/initial conditions, nonlinearity and limited applicability. In conclusion, the analysis of PDEs plays a crucial role in understanding multi-variable functions and has revolutionized industries through applications in areas like fluid dynamics and electromagnetics.