Magnetic resonance technique may successfully be applied to determine some basic parameters such as g-factor, magnetization M(s) or anisotropy energy constant K(u) in thin magnetic films. These parameters are obtained from a ferromagnetic resonance experiment when uniform precession of M(s) takes place. From spin-wave resonance one may extract very valuable information on the exchange constant A or the surface conditions characterized by the surface anisotropy energy (or pinning parameters rho). In fact, it is only spin-wave resonance or similar techniques which allow for measurements of A, rho or the coupling constant K(c) between ferromagnetic sublayers in multilayered structure. The magnetic phase diagram, temperature dependence of the spin-waves stiffness constant, and the anisotropy energy constant may also be listed as less common examples of spin-wave resonance technique application for the investigation of thin films. This paper presents a theoretical approach to typical examples of experimental results and their interpretation from spin-wave resonance measurements.