Understanding dwarf galaxies is crucial for verifying and improving our broader picture of galaxy formation in the universe. They contain so few stars that their gravitational effects are almost entirely dominated by dark matter. They are also exquisitely sensitive to stellar processes that can heat and eject gas, which in turn prevent further stars from forming. The combination of these two factors make them enticing and yet challenging to study: they hold the potential to help identify the nature of dark matter, but first we must vastly improve our understanding of the interaction between stars, interstellar medium, and the universe beyond. I will review recent observational and theoretical progress in these areas, including through the “genetically modified galaxies” programme, which focuses on how the formation history of galaxies determine their present-day properties.