I review our present understanding of a collection of bosons on a lattice. The bosons interact with each other and may have random site energies. Superfluid, Mott insulating, and glassy phases are possible at T=0. The relevance of these results to experimental systems such as He4, disordered superconductors, and Josephson junction arrays, is discussed. Analytical and numerical results, as well as open questions are pointed out.