Observations of binary stars in the Galactic field and in star-forming regions as well as surveys of star-formation in nearby molecular clouds have shown stars to form in embedded clusters.These are the “fundamental building blocks” of galaxies and their stellar populations have systematically varying properties.A particularly important property is that they disrupt binaries to a varying degree,and that extreme cases have top-heavy stellar IMFs.I will show that many properties of dwarf to massive galaxies can be derived with this notion by summing up all frech stellar populations in the embedded clusters.An important result is dynamical population synthesis which allows predictions of binary star populations in different types of galaxies.Another important result is the prediction of a systematically varying galaxy-wide IMF.According to this IGIMF theory dwarf galaxies have top-light galaxy-wide IMFs,while galaxies with high star formation rates have top-heavy IMFs,as is observed.