Mass, a concept familiar to all of us, is also one of the deepest mysteries in nature.  Almost all of the mass in the visible universe, you, me and any other stuff  that we see around us, emerges from QCD, a theory with  a negligible microscopic mass content. How does QCD and the family of gauge theories it belongs to generate a mass?

This class of non-perturbative problems remained largely elusive despite much effort over the years. Recently, new ideas based on compactification have been shown useful to address some of these. Two such inter-related ideas are circle compactifications, which avoid  phase transitions and  large-N volume independence. Through the first one, we realized the existence of a large-class of  "topological molecules", e.g. magnetic bions, which generate mass gap in a class of compactified gauge theories. The inception of the second, the idea  of  large-N volume independence is old. The new progress is the realization of its first working examples. This property allows us to map a four dimensional gauge theory (including pure Yang-Mills) to a quantum mechanics at large-N.