  In this article the production of $K^+$ at energies close to the threshold is
studied in detail. The production mechanisms, the influence of in-medium
effects, cross sections, the nuclear equation of state and the dynamics of the
nucleons on the kaon dynamics are discussed. A special regard will be taken on
the collision of Au+Au at 1.5 GeV, a reaction that has recently been analyzed
in detail by experiments performed by the KaoS and FOPI collaborations at the
SIS accelerator at GSI.
