Absolute B-band magnitude at peak is plotted against the light-curve decline rate Δm₁₅(B) (Phillips 1993), including the 1991bg-like, 2002es-like, 1999T-like, subluminous events, and normal events. The samples are taken from multiple sources (Filippenko et al. 1992a,b; Taubenberger 2017; Krisciunas et al. 2017; Scolnic et al. 2018; Li et al. 2022b). The solid curve represents the best-fit relation proposed by Phillips et al. (1999) using the CfA3 data. Different classes of objects discussed in this chapter are highlighted by different colors and SN 2021wuf is represented by a black rhombus.