Historically it was both a surprise and a theoretical triumph to find out that anti-matter exists at all. As we learnt more about the Universe, we are surprised by something very different - why do we almost exclusively see matter. The fact that throughout most of human history, we were oblivious to the existence of anti-matter is a testament to the dominance of matter over anti-matter. Looking at the earliest light and earliest elements in the Universe, we find that this imbalance goes back to at least when the Universe was a mere second old. However, inflation would wipe out any difference between matter and anti-matter and all processes we know of cannot create such an asymmetry. I will review the three main answers physicists have given to this fundamental question and what challenges face the community trying to shed light on this issue.