Here we will present some spectroscopic methods for emission gas research in the emission line region of Active Galactic Nuclei (AGNs): (1) We will demonstrate the possibility to use the Boltzmann‐plot method to estimate the physical conditions in the broad line regions (BLRs); (2) We will discuss the applicability of so called “Gaussian method” for spectral line shape investigation of narrow line regions (NLRs) and BLRs; (3) We will present a method to fit the line profiles with a kinematically complex model. We apply a two‐component model assuming that the line wings originate in a very broad line region (VBLR) and the line core in an intermediate line region (ILR) of AGNs. The VBLR is assumed to be an accretion disk and the ILR a spherical emission region; (4) Also, a model for fitting of the broad absorption lines in quasars will be discussed. © 2004 American Institute of Physics