  The present status of tests of QED with highly charged ions is reviewed. The
theoretical predictions for the Lamb shift and the transition energies are
compared with available experimental data. Recent achievements in studies of
the hyperfine splitting and the $g$-factor isotope shift with highly charged
ions are reported. Special attention is paid to tests of QED within and beyond
the Furry picture at strong-coupling regime. Prospects for tests of QED at
supercritical fields that can be created in low-energy heavy-ion collisions are
discussed as well.
