Chaperones are unique remodeling proteins that participate in a great number of intracellular processes and are involved in the correction of protein structure, the prevention of the aggregation of misfolded proteins, the destruction of protein aggregates, and also the unfolding of native protein targets for their translocation across a membrane. In addition to this, Chaperones assist in the dismantling of active oligomers into inactive unfolded monomers for their subsequent photolytic degradation and the assembly of folded subunits into protein assemblies and specific complexes. Data on the structure and functioning of molecular chaperones from five basic families are summarized in the review.