2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/48216I discuss the bound state quark dynamics focusing on the nonperturbative interaction and the flux tube structure.20 pages, Latex, worldsci.sty, 10 Figures. Plenary talk given at the 3rd International Conference on Quark Confinement and the Hadron Spectrum (ConfinementIII), Jefferson Lab, USA, June 7-12, 1998; corrected some typosHigh Energy Physics - PhenomenologyHigh Energy Physics - LatticeHigh Energy Physics - Theorytext