Bosons on a disordered lattice (Bose-Hubbard model) exhibit three phases: superfluid (phase-coherent), Mott insulator (commensurate filling), and Bose glass (Anderson-localized, gapless, non-superfluid). The Bose glass always intervenes between Mott insulator and superfluid in 1D/2D disordered systems (Fisher et al. 1989).