The conduction band is the range of electron energies enough to free an electron from binding with its atom to move freely within the atomic lattice of the material as a 'delocalized electron'. Various materials may be classified by their band gap: this is defined as the difference between the valence and conduction bands.
- In non-conductors, aka insulators, the conduction band is higher than that of the valence band, so it takes infeasibly high energies to delocalize their valence electrons. They are said to have a non-zero band gap.
- In conductors, such as metals, that have many free electrons under normal circumstances, the conduction band overlaps with the valence band--there is no band gap.
- In semiconductors, the band gap is small. This explains why it takes a little energy (in the form of heat or light) to make semiconductors' electrons delocalize and conduct electricity, hence the name, semiconductor.
Semiconductor band structure
See electrical conduction and semiconductor for a more detailed description of band structure.
See also 
- Band Theory
- Electrical conduction for more information about conduction in solids, and another description of band structure.
- Fermi sea
- Semiconductor for a full explanation of the band structure of materials.
- Valence band
- This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C".
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