In this part, we detail the observational data most recent of the supernovæ of the Ia type by distinguishing the spectroscopy, photometry as well as abundances and the galaxies hosts. Then, we describe how these observations make it possible to impose to a certain number of constraints on the nature of the stellar systems progéniteurs, on the mechanisms of ignition and propagation of the explosion and finally on the physique of the transport of energy towards outside.
Dwarf white + star on the principal sequence