Stripped of astrophysical jargon and millennial tradition, supernova cosmology can be seen as a purely epistemic field that considers its objects (type Ia supernovae: SNæ Ia) only insofar as the concordance of their properties makes them useful for inference of background quantities (cosmographic parameters). This chapter briefly introduces the basic concepts in the field, related both to the physical interpretation of SN Ia explosions and to modelling the dynamics of the Universe.