Evolution of AGN and Stellar Formation through Radio Surveys

The change in the slope of the radio source counts suggests the emergence of a new population of radio galaxies at mJy and sub-mJy levels. Our understanding of such faint radio sources has advanced over the last decade through increasingly sensitive radio surveys and follow-up works at optical wavelength. The sub-mJy population seems to include both star forming galaxies and classical (AGN-powered) radio sources, but the relative importance of the two classes is still debated. Recent results are reviewed and discussed.