Page "Electromagnetic field" Paragraph 31

If only the electric field () is non-zero, and is constant in time, the field is said to be an electrostatic field.

Similarly, if only the magnetic field () is non-zero and is constant in time, the field is said to be a magnetostatic field.

However, if either the electric or magnetic field has a time-dependence, then both fields must be considered together as a coupled electromagnetic field using Maxwell's equations.