[en] The accumulating evidence for clustering of produced particles in inelastic hadron scattering is reviewed, and described in terms of a two-step mechanism of production and decay of clusters. First hints for this phenomenon came from the investigation of multiplicity distributions, but the real need for clusters arose in order to account for inclusive two-body correlations. After a review of these facts, the connection between inclusive and semi-inclusive distributions is worked out in detail. The charge structure of clusters is then studied by consideration of charge transfer distributions in phase space. Finally an analogy between this concept of clusters and the idea of gluons and partons is mentioned. Although all these features are suggestive and the model describes the data reasonably well, it is still unclear whether real clusters exist or whether they are a mere practical parametrization of an unknown mechanism. (Auth.)