How do superconductors carry electricity without resistance?

Superconductivity was discovered by Heike Kamerlingh Onnes in 1911 when he found that mercury lost all electrical resistance at very low temperatures. In a superconductor, electrons form paired states and move through the material in a coordinated quantum manner. This eliminates ordinary resistance and allows persistent currents. Superconductors also expel magnetic fields, a property called the Meissner effect. Many superconductors need extremely cold temperatures, though high-temperature superconductors can work at comparatively warmer temperatures, still far below room temperature.