Top: representative galaxies of different stellar masses: a giant elliptical (M_⋆ ∼ 2.5 × 10¹¹ M_⊙), a Milky Way-like galaxy (M_⋆ ∼ 2.5 × 10¹⁰ M_⊙), a UDG and dwarf galaxy (M_⋆ ∼ 10⁸ M_⊙). All galaxies are shown to the same physical scale and a similar depth in surface brightness. Bottom: stellar mass density profiles of the same galaxies. The coloured ticks in the upper x-axis mark the location of R_e. Similar ticks in the lower x-axis mark the location of R₁.