First Stars, Reionization and Gamma-Ray Bursts

Gamma-Ray Bursts represent unique tools to study the early phases of cosmic evolution, the formation of the first stars and galaxies. Absorption line spectra of these sources located in the Epoch of Reionization might provide us with key information about these remote, and yet fundamental, stages of cosmic history. I will briefly review these issues, highlighting the immense leap that the \TH mission could represent for finding answers to the many fundamental open questions.