A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and the magnetic field. A permanent magnet′s magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets.
In addition, a magnetic field that varies with location will exert a force on a range of non-magnetic materials by affecting the motion of their outer atomic electrons. Magnetic fields surround magnetised materials, and are created by electric currents such as those used in electromagnets, and by electric fields varying in time. Since both the strength and direction of a magnetic field may vary with location, they are described as a map assigning a vector to each point of space or, more precisely—because of the way the magnetic field transforms under mirror reflection—as a field of pseudovectors.