Our Universe began almost 14 billion years ago as a hot soup of energy and elementary particles. With modern telescopes we can peer back into the distant past and see the Universe as it was at early times, before the first stars and galaxies lit up the sky. We’ve learned that on the largest scales the Universe can be described by a few simple numbers, but on smaller scales incredible complexity arises.

I will discuss the major observations that have led to this picture, with a focus on the evidence that our Universe is dominated not by the stuff that we can observe, but by dark matter and dark energy whose nature is still unknown to us.