First stars, first galaxies and black holes.

Up to now, the epoch between 400000 years and 1 billion years after the Big Bang is still largely $terra incognita$. With the formation of the first sources of radiation, stars and Black Holes (BH) this era saw what is often referred to as the transition from the dark ages to cosmic dawn. Despite the still rather scarce observational data, impressive progress has been made in understanding the physical properties of the earliest galaxies, and specifically of those possibly responsible for the reionization of the Universe. In this contribution, I will review the emerging theoretical framework for how stars, galaxies, and black holes transformed the early universe in light of the first observations of the James Webb Space Telescope (JWST) that will allow us to confront theory with observations at the edge of time.