The observed properties and evolution of galaxies in the Universe require the 
existence of feedback mechanisms regulating the star formation and finally 
quenching it. The presence of winds, possibly transporting the gas outside 
the virial radius, has been confirmed observationally in local and high 
redshift objects. 
In this talk, I will briefly review how scientist have confirmed the 
presence of heavy elements outside galaxies using the observation of 
QSO absorption lines and I will present and discuss new results based on 
the highest signal-to-noise ratio, high resolution QSO spectrum ever obtained.