Muons originate from the decay of hadrons, produced in interactions of the primary cosmic particles with the nuclei of the atmosphere. The observation of the features of the muonic component, arising from the cascading processes induced by the primary particle, a phenomenon called extensive air shower (EAS), provides interesting information about the nature of the primary and its interactions. We illustrate this information potential by: (i) studies of the longitudinal development of EAS by measurements of the relative arrival time distributions of muons the KASCADE experiment, (ii) studies with the Bucharest electromagnetic calorimeter WILLI for energy estimates of TeV muons and for determination of the charge ratio of the atmospheric muon flux.

PACS numbers: 11.30.--j, 95.30.Cq