We derive a posteriori estimates for the difference between exact solutions and approximate solutions to boundary-value problems in terms of local norms. The diffusion problem, linear elasticity and generalizations to other boundary-value elliptic problems are considered. Computable estimates for the deviation from the exact solution are also obtained in terms of linear functionals. Unlike published works of other authors, the construction of such estimates is not connected with any analysis of the adjoint boundary-value problem. On the basis of multiplicative inequalities, local estimates in certain norms subject to the energy norm are derived. Bibliography: 10 titles.