Critical temperature is the threshold below which a material enters a superconducting state. In that state, electrical resistance drops to zero and the material can carry current with exceptional efficiency. The exact value depends on the substance, its composition, pressure, and how it was prepared.
This term matters because a superconducting claim is only meaningful if the measured temperature is real, reproducible, and tied to stable material behavior. A high critical temperature is attractive for practical devices, but the result becomes more convincing when it is reached under ordinary ambient pressure and can be verified by other labs. In experiments, critical temperature appears as the point where resistance measurements, magnetic response, or other signatures change sharply. For defense against false or overstated claims, researchers check whether the transition is repeatable, whether the sample remains stable, and whether the measurement setup supports the reported threshold.