It is now widely accepted that the reionization of the Universe completed approximately at redshift 6, however the nature of sources that reionized the Universe is hotly debated. Traditional viewpoint is that a major part of the photon budget required for reionization was provided by galaxies at the faint-side of the luminosity function. However, this may not be true as I will discuss in this talk. I will show that the galaxies at the bright-side of the luminosity function provided the majority of the ionizing photons; such galaxies already within the detection capability of the Hubble Deep Field. This idea is further supported by recent observations of escaping Lyman continuum from a few nearby galaxies, and it agrees well with existing constraints on reionization from CMB and kSZ effect. I will also discuss the connection between the physical processes that shaped early galaxies and the abundance patterns of metal poor stars in the Milky Way today.