Physics of strange matter

Relativistic heavy ion collisions offer the possibility to produce exotic metastable states of nuclear matter containing (roughly) equal number of strangeness compared with the content in baryon number. The reasoning of both their stability and existence, the possible distillation of strangeness necessary for their formation and the chances for their detection are reviewed. For the latter, emphasis is put on the properties of small lumps of strange quark matter with respect to their stability against strong or weak hadronic decays. In addition, implications in astrophysics like the properties of neutron stars and the issue of baryonic dark matter will be discussed. (author)