The Fermi Level is a concept in solid-state physics that represents the highest energy level occupied by electrons at absolute zero temperature. It helps determine the electrical properties of materials, indicating whether a material behaves as a conductor, semiconductor, or insulator. In semiconductors, the Fermi Level can shift depending on temperature and doping, which is the process of adding impurities to alter electrical properties. Understanding the Fermi Level is crucial for designing electronic devices like transistors and diodes, as it influences how electrons move within materials and how they interact with external electric fields.