My research focusses on the formation and evolution of the first galaxies in the Universe: a few hundred thousands years after the Big Bang our Universe entered the cosmology Dark Ages, a period where there were literally no sources of visible light. During this period however gravity continued to act upon matter producing accumulations of gas and dark matter. A few hundred million years later the first stars were able to form lighting up the Universe and bringing an end to the Dark Ages. These stars produced intense radiation which ionised their surroundings. As they died these stars also enriched their surroundings with elements heavier than helium enabling the formation of the first planets and ultimately life.