# What are differential equations?

Differential equations are usually classified into two general categories: partial differential equations, which are also called partial derivatives, and ordinary differential equations.

Partial derivatives can be first-order, second-order, or higher order, and they’re what you get when you have a multivariable equation, but take the derivative of that equation with respect to just one variable.

Ordinary differential equations are equations that include a derivative, and that derivative can be of any order (first-order, second-order, or higher-order). Ordinary differential equations are more commonly classified into other specific types of differential equations, like linear differential equations, separable differential equations, and exact differential equations.

0:18 // What are partial differential equations (partial derivatives)?

1:31 // What are ordinary differential equations?

2:53 // What are linear differential equations?

3:22 // What are separable differential equations?

4:26 // What are exact differential equations?

4:52 // Summary