Mass, and its origin, are mysterious. We know that the mass of everyday objects comes from the nucleons (protons and neutrons) in the nuclei of atoms. Simply count the number of these nucleons and you have a good idea of an object’s mass. According to quantum chromodynamics (QCD), each proton or neutron consists of three quarks and some gluons. However, the combined mass of the quarks and gluons is only 1% of a nucleon’s – what gives? Interactions between these tiny particles are the problem: they look simple in one way, but as interactions accumulate, supercomputers are needed to keep track of them. Over the past decade, looking at interactions as a way of understanding QCD has blossomed into a successful enterprise, solving old problems in physics and aiding new experiments. Beyond the mass of the proton (and you), these tools can broadly probe the mysteries of QCD to address problems in particle, nuclear and astrophysics.