Definition:Differential Equation

Definition
A differential equation is a mathematical equation for an unknown function of one or several variables relating:
 * $(1): \quad$ The values of the function itself
 * $(2): \quad$ Its derivatives of various orders.

Ordinary, Partial and Total Differential Equations
There are three types of differential equation:

Linear and Non-Linear
Differential equations can also be classified as to whether they are linear or non-linear.