In this review we discuss the chaotic dynamics (both classical and quantal aspects) of a simple atomic system, namely hydrogen atom interacting with time independent and time dependent external fields. These include: i) static electric field, ii) static magnetic field, iii) combined electric and magnetic fields, in parallel and perpendicular configuration, iv) instantaneous and generalized van der Waals field, v) mass anisotropy and vi) linearly and circularly polarized microwave fields.
