Due to the discovery of renormalon cancellation, it became possible to describe
the nature of a heavy quark-antiquark 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 prediction.