Atoms in weak broadband quasi-resonant fields - light shifts atoms in linear superpositions of Zeeman sublevels-Zeeman coherences atoms in strong radiofrequency fields - the dressed-atom approach in the RF domain atoms in intense resonant laser beams - the dressed-atom approach in the optical domain the radiative cascade of the dressed atom - photon correlations and quantum jumps atoms in high-frequency fields or in the vacuum field - simple physical pictures for radiative corrections atomic motion in laser light - laser cooling and trapping.