Due to the discovery of renormalon cancellation, it became possible to describe the nature of a heavy quark­antiquark system (such as bottomonium) based on perturbative QCD, both qualitatively and quantitatively. Accordingly, interpretaions of the heavy quark mass and interquark force have been modified considerably. I overview what has been understood and some of theoretical progress since then. The UV part of the interquark potential can be computed in perturbative QCD. We show that a “Coulomb+linear” potential is obtained as the prediction.