The wave equation describes how electric and magnetic fields propagate through space.

The general form of the wave equation for electric fields is given by: $$\nabla^2 \textbf{E} - \frac{1}{c^2} \frac{\partial^2 \textbf{E}}{\partial t^2} = 0, \tag{1}$$ where $\nabla^2$ is a differential operator called the Laplacian operator, $c$ is the speed of light and $\frac{\partial^2 \textbf{E}}{\partial t^2}$ is the second partial derivative of the electric field with respect to time.

The wave equation for magnetic fields is virtually identical to equation (1).