This article analyzes the features of the interaction of a nonmonochromatic multifrequency laser radiation field with an isolated atom. Multiphoton excitation and nonlinear ionization of atoms under conditions in which the atomic levels are perturbed by the laser radiation field are treated. The extreme cases of interaction of an atom with a field are discussed in detail--the case of a broad laser radiation spectrum (fast field fluctuations) and the case of a narrow spectrum (slow fluctuations). The experimental data available in the scientific literature relevant to the set of questions under discussion are analyzed.