...and just to be complete, The Ampere-Maxwell Law
The Ampere-Maxwell law in integral form is the following:
$$ \oint_C \vec{B} \circ d\vec{l} = \mu_0 \bigg(I + \varepsilon_0 \frac{d}{dt} \int_S \vec{E} \circ \hat{n} dA \bigg) $$It states that the circulation of the magnetic field \( \vec{B} \) around a closed loop \( C \) is proportional to the electric current \( I \) that passes through the surface \( S \) bounded by \( C \), and also the time derivative of electric flux that passes through this surface.
In other words, magnetic fields which form closed loops are produced by electric currents, changing electric flux, or both simultaneously!
