An "Energy Band" refers to a range of energy levels that electrons can occupy in a solid material, particularly in semiconductors and insulators. These bands are crucial for understanding how materials conduct electricity. The two main types of energy bands are the valence band, which contains electrons involved in bonding, and the conduction band, where free electrons can move and conduct electricity. The gap between the valence band and the conduction band is known as the band gap. Materials with a small band gap can easily conduct electricity, while those with a large band gap are typically insulators. Understanding energy bands helps in the design of electronic devices like transistors and solar cells.