Several problems in the theory of van der Waals forces are reviewed: the interaction of atoms, molecules, and small particles of condensed matter at large distances; the van der Waals interaction of atoms with the surface of condensed matter; and the interaction between macroscopic condensed objects of various shapes. These questions have attracted considerable interest in the literature in recent years. Numerous results on these questions are given. All topics are discussed from a common standpoint to the extent possible, on the basis of the understanding of the fluctuational origin of van der Waals forces. Analysis of the physics content of the theoretical results on van der Waals forces is emphasized.