The confinement problem

Confinement of quarks is sometimes taken as some kind of dogma in the contemporary theory of strong interactions - quantum chromodynamics (QCD). As scientists the authors should not be content with that. Rather they should try to formulate what they mean by ''permanent confinement'' more precisely and then see whether the theory has this property or not. In these lectures the author first looks at some possible interpretations of ''confinement'' and their shortcomings and then turn to the most widely used rather pragmatic definition based on the somewhat unphysical notion of infinitely heavy external sources. The author describes what is known - or more precisely what I know - about the problem in this more limited sense and try to bring into focus some aspects that are insufficiently understood