Type-II superconductors are materials that can conduct electricity without resistance below a certain temperature, known as the critical temperature. Unlike Type-I superconductors, which completely expel magnetic fields, Type-II superconductors allow magnetic fields to partially penetrate them in specific regions called vortices. These materials are often made from complex compounds, such as niobium-titanium or high-temperature superconductors like YBCO. They are widely used in applications like magnetic resonance imaging (MRI) machines and particle accelerators due to their ability to maintain superconductivity in higher magnetic fields and temperatures compared to Type-I superconductors.