Review of SIS experimental results on strangeness

A review of meson emission in heavy-ion collisions at incident energies aro und 1-2 A GeV is presented. It is shown how the shape of the spectra and th e various particle yields vary with system size, with centrality and with i ncident energy. A statistical model assuming thermal and chemical equilibri um and exact strangeness conservation (i.e. strangeness conservation per co llision) explains most of the observed features. Emphasis is put on the: study of K+ acid K- emission. Within the framework of this statistical model it is shown that the experimentally observed equa lity of K+ and K- rates at threshold corrected energies roots - roots(th) i s due to a crossing of two excitation functions. Furthermore, the independe nce of the K+ to K- ratio of the number of participating nucleons observed between 1 and 10 A GeV is consistent with this model. The observed flow eff ects are beyond the scope of this model.