Appears in collection : 2026 IHES Summer School – Cosmological Correlators

The basis of modern observational cosmology is the CMB and galaxy surveys. These lectures will start by giving an overview of the various surveys, and then diving into what they have done or will do. This includes precise determination of parameters via the two-point functions and upper limits on PNG. Then, I will provide a few examples that move beyond the two-point function, with the examples of CMB lensing and small scale clustering in lensing and galaxy surveys. I’ll conclude by outlining Field Level Inference as a tool that may eventually be able to map out primordial perturbations.