Nonperturbative QCD: confinement and deconfinement

After a short exposition of field correlators in the QCD vacuum and the recently discovered Casimir scaling phenomenon, the origin of confinement in QCD is discussed and two possible mechanisms are suggested, which can be checked by new lattice measurements. Screening of confinement due to sea quarks is discussed and quantitatively explained. Deconfinement is introduced via the colorelectric field evaporation and the transition temperature Tc is found numerically in good agreement with lattice measurements. The Tc dependence on Nc and nf is also predicted and agrees with the recent lattice data.