The distinction between valence and conduction bands is discussed. Insulators, semiconductors, metals. Electrons and holes definition. Effective mass; sign convention of charge, mass and mobility. Semi-metals and narrow gap semiconductors. Band parameters for typical semiconductors, table. Constant energy surfaces in Brillouin zones. Effective mass in real bands, in conduction and valence bands for various semiconductors, table. Band gaps and higher bands in typical semiconductors, tables. Hole effective mass and valence band splitting for typical semiconductors, splitting, table. Probing of bands and measuring effective masses with cyclotron resonance is discussed. Distinction of momentum effective mass, and effective mass at higher energies is given the band gap discussion, diagram for different types of semiconductors. Band gap variation with temperature and pressure, with alloy composition; gap bending, table of bowing parameters. Direct and indirect band gap discussion and table. Gap narrowing with heavy doping, shift of Fermi level into gap. Bands in superlattices. Mini bands, electron transport. Bands in ultrathin superlattices. Density of states in mini bands. One- two- and zero-dimensional quantum wells. Electronic states in micro crystallites. Bands in amorphous semiconductors. Use of supercomputers is indicated.