The Cosmic Microwave Background (CMB) is one of the most studied probes for cosmological measurements. I will be presenting the latest Data Release 6 (DR6) from the Atacama Cosmology Telescope (ACT), which made the most precise measurements of the small-scale temperature and polarization modes of the CMB over a quarter of the sky. With these constraints, I present the most stringent constraints on the ΛCDM model we have to day, as well as improved constraints on beyond-ΛCDM physics since the Planck satellite. I discuss how these constraints fit within current developments in observational cosmology, and how future observations of the CMB with the new Simons Observatory (SO) will improve beyond this.
