Coulomb interactions in Anderson insulators

We review the main theoretical aspects concerning Coulomb glasses. that is systems with states localized by disorder and long-range interactions betwe en their particles. The numerical algorithms available for their simulation s are explained. We analyse tunnelling experiments and the role of screenin g by metallic electrodes. We study the mechanism for variable-range hopping conductance in these systems and in particular the role of many-electron c orrelations. Recent relaxation experiments and the possible glass transitio ns are reviewed. Finally, we describe different approaches to incorporate q uantum effects in the study of Coulomb glasses.