  The consequences of energy injection associated with stellar activity in
galaxies have been often referred to as ``feedback effects''. Assessing the
detailed physics and the role of such effects are central issues in modern
theories of galaxy formation and evolution. In these Lectures we present a
brief review of various aspects related to feedback with particular emphasis to
those occurring when the universe was only 100 Myr old, an epoch now commonly
known as the the Cosmic Dawn, when the first galaxies and the stars within them
brought the universe back into the visible ages.
