ABstract. We use the cannonball (CB) model ofgamma ray bursts (GRBs) and their afterglows (AGs) toanalyze the observational data on X-ray flashes (XRFs)and their AGs. We show that the observations support theCB-model interpretation that XRFs, like GRBs, are pro-duced by the explosions of core-collapse supernovae (SNe)akin to SN1998bw, by jets of highly-relativistic CBs. TheXRFs and GRBs are intrinsically identical objects, butthe XRFs are viewed from angles (relative to the jet di-rection) which are typically a few times larger than thetypical viewing angles of “classical”, long-duration GRBs.There should be XRFs, not observedso far, with durationssimilar to those of short GRBs.Key words. X rays: flashes— gamma rays: bursts—supernovae: general 1. Introduction and summary By definition, XRFs are GRB-like bursts of photons whose“peak energy”, E p , is below 40 keV (roughly speaking, E p is the maximum of the distribution ν F ν = E 2 dN γ /dE).They are rich in X-rays but relatively poor in γ-rays, asimplied by their name. They were discovered with theWide-Field Camera of the Beppo-SAX satellite, but theywere not seen above 40 keV with its GRB Monitor (Heiseet al. 2001). They were detected by BeppoSAX at a rateof 4 per year, indicating a population not very muchsmaller than that of GRBs