  Recent results from the KASCADE extensive air shower experiment are
presented. After briefly reviewing the status of the experiment we report on
tests of hadronic interaction models and emphasize the progress being made in
understanding the properties and origin of the knee at $E_{knee} ~ 4.10^{15}
eV. Analysing the muon- and hadron trigger rates in the KASCADE calorimeter as
well as the global properties of high energy hadrons in the shower core leads
us to conclude that QGSJET still provides the best overall description of EAS
data, being superior to DPMJET II-5 and neXus 2, for example. Performing high
statistics CORSIKA simulations and applying sophisticated unfolding techniques
to the electron and muon shower size distributions, we are able to successfully
deconvolute the all-particle energy spectrum into energy spectra of 4
individual primary mass groups (p, He, C, Fe). Each of these preliminary energy
distributions exhibits a knee like structure with a change of their knee
positions suggesting a constant rigidity of R ~ 2-3 PV.
