The direction of the magnetic field at any point is tangent to the magnetic field line at that point. The aim of this lecture is to present on Magnetic Field Lines. Magnetic field lines are useful for visually representing the strength and direction of the magnetic field. This lines are continuous and unbroken, forming closed loops. Magnetic field lines are defined to begin on the north pole of a magnet and terminate on the south pole. It exerts magnetic forces and is surrounded by a magnetic field that is strongest near the North and South magnetic poles.