Methods of calculation of NLTE model atmosphere are discussed. The NLTE trace
element procedure is compared with the full NLTE model atmosphere calculation.
Differences between LTE and NLTE atmosphere modeling are evaluated. The ways of
model atom construction are discussed. Finally, modelling of expanding
atmospheres of hot stars with winds is briefly reviewed.Comment: in Determination of Atmospheric Parameters of B-, A-, F- and G-Type
Stars, E. Niemczura et al. eds., Springer, in pres