The Cosmic Microwave Background (CMB) encodes the history of our Universe, spanning enormous ranges of time and physical scale—from conditions in its earliest moments to the distribution of matter on the largest scales. Precision measurements of the CMB provide constraints on a diverse set of phenomena, including inflationary physics, light relic particles, dark matter, dark energy, and a broad range of astrophysical processes.

In this talk, I present results from the Atacama Cosmology Telescope (ACT) and discuss the progress that will be made with its recently commissioned successor, the Simons Observatory.