In astronomy, axial tilt, known to astronomers as obliquity, is the angle between an object's rotational axis, and its orbital axis, or, equivalently, the angle between its equatorial plane and orbital plane. It differs from orbital inclination.
Read more about Axial Tilt: Introduction, Obliquity of The Ecliptic (Earth's Axial Tilt), Other Objects of The Solar System, Extrasolar Planets