$\nabla \cdot \vec{\mathbf{B}} = 0$ | divergence of $\vec{\mathbf{B}}$ is zero
$\nabla \times \vec{\mathbf{E}}\, +\, \frac1c\, \frac{\partial\vec{\mathbf{B}}}{\partial t} = \vec{\mathbf{0}}$ | curl of $\vec{\mathbf{E}}$ is proportional to the rate of change of $\vec{\mathbf{B}}$