Type-I superconductors are materials that exhibit superconductivity at very low temperatures, typically below a critical temperature. They completely expel magnetic fields from their interior, a phenomenon known as the Meissner effect. This results in a perfect diamagnetism, allowing them to levitate magnets above their surface. These superconductors are usually elemental metals, such as lead or mercury. They have a single critical magnetic field, beyond which they lose their superconducting properties. Type-I superconductors are simpler in behavior compared to Type-II superconductors, which can allow magnetic fields to penetrate in certain regions.