  Since the discovery of superconductivity at 200 K in H3S [1] similar or
higher transition temperatures, Tcs, have been reported for various
hydrogen-rich compounds under ultra-high pressures [2]. Superconductivity was
experimentally proved by different methods, including electrical resistance,
magnetic susceptibility, optical infrared, and nuclear resonant scattering
measurements. The crystal structures of superconducting phases were determined
by X-ray diffraction. Numerous electrical transport measurements demonstrate
the typical behaviour of a conventional phonon-mediated superconductor: zero
resistance below Tc, the shift of Tc to lower temperatures under external
magnetic fields, and pronounced isotope effect. Remarkably, the results are in
good agreement with the theoretical predictions, which describe
superconductivity in hydrides within the framework of the conventional BCS
theory. However, despite this acknowledgment, experimental evidence for the
superconducting state in these compounds has recently been treated with
criticism [3, 4], which apparently stems from misunderstanding and
misinterpretation of complicated experiments performed under very high
pressures. Here, we describe in greater detail the experiments revealing
high-temperature superconductivity in hydrides under high pressures. We show
that the arguments against superconductivity [3, 4] can be either refuted or
explained. The experiments on the high-temperature superconductivity in
hydrides clearly contradict the theory of hole superconductivity [4] and
eliminate it [3].
