Tetra-quarks, penta-quarks and the like: old and new views

Abstract

In this talk, after a short overview of the history of the discovery of tetra-quarks and penta-quarks, we will discuss a possible interpretation of such states in the framework of a 40-years-old "string junction" picture that allows a unified QCD description of ordinary mesons and baryons as well as multi-quark resonances.