Theoretical search for collective effects in multiparticle production

The properties of QCD vacuum and of the confinement of quarks and gluons certainly influence the multiparticle production processes. Some phenomenological attempts at the consideration of related collective effects and the possibilities of their experimental detection are briefly discussed. Particular consideration is given to the correlation characteristics of pion systems, statistical and hydrodynamic analogies, the problem of phase transition from a quark—gluon plasma to a multipion state, and the possible modifications of the evolution equations of the quark—gluon jets. The presentation is somewhat simplified and could be interesting for those just entering the field.