The subject deals with electronic structure of solid crystalline matter. The subject starts with relation between crystal symmetry, electronic structure and its physical properties. Then, general principles of ab-initio calculations are presented, together with discussion of related approximations, Knowing the electronic structure, many physical properties can be expressed, which is demonstrated on example of elastic constants, lattice vibrations, electrical and thermal conductivity as well as on example of optical properties of solids. Later, the spin-polarization in solids (magnetic ordering, e.g. ferro-, antiferro-, ferri-, spin-spiral etc.) is discussed. Finally, the importance of spin-orbit interaction and its effect on many physical properties is demonstrated. Practical example, e.g. calculation of a Si thermal expansion, will be delivered on-line.