We will review both theoretical and obsevational aspects of gravitational wave backgrounds of cosmological origin. We will present a classifcation of backgrounds and a quantification of our ability to use them as a probe of early Universe phenomena, opening a new observational window to energy scales well above the reach of any terrestrial means

Understanding stellar structure and evolution significantly impacts our understanding of the tight-knit evolution of galaxies and exoplanet systems. However, hidden behind the luminous layers of the stellar atmosphere, the deep interior of a star is eluding from direct measurements. The seismic study of waves propagating the deep interior provides

Gravitational-wave observations have revealed the population of stellar remnants from a new angle. Yet their stellar progenitors remain uncertain, in particular in the case of black holes. At least a fraction of these progenitors is believed to form in isolated binary systems. In this talk, I will discuss how binary mass transfer affects the late