Please explain me the magnetic inclination or dip in detail with reasoning.

Magnetic inclination or magnetic dip is the angle (I) between the horizontal plane and the magnetic field vector. It is the angle made by a compass needle with the horizontal at any point on the Earth's surface. Moving closer to magnetic poles results in one side of the compass needle pointing downwards. Between the magnetic poles there is an area called the magnetic equator where inclination or the magnetic dip angle is zero; the magnetic field vector does not have a vertical component (Z) in this area. To the north of the magnetic equator, the north end of the compass needle points downward, both I and Z are positive. To the south of the magnetic equator, the south end of the needle points downward, that is I and Z are both negative.  Positive values of inclination indicate that the field is pointing downward, into the Earth, at the point of measurement.