The solution of an inverse scattering problem is defined in this paper as the extraction of physical information (viz., composition and shape) from the (active) echoes returned by an underwater elastic target. This pertains to the general area of target identification. In this sense, to solve an inverse scattering problem may be relatively simple in the low- or the high- frequency regions of the target's spectra, because of the number of simplifying approximations that can usually be made in these two spectral regions. However, for the intermediate or resonance region of all scatterers, the above mentioned approximations usually do not hold, and either exact solutions or novel types of approximations are required. This makes the inversion of the scattered waveforms extremely hard. A certain level of success has been achieved by exploiting the presence of certain resonance features that manifest themselves in the resonance region of the scattering cross-section (SCS) of submerged elastic targets. Although the main interest over the years has been the isolation or extraction of the resonance features contained within the SCS of a penetrable target, little has been said about what to do with these resonances once they are isolated. This resonance extraction process can be carried out theoretically, experimentally, and computationally, by means of either CW or pulsed interrogating waveforms. The paper shows some (idealized) examples to illustrate how the resonances, once they are isolated by either means, can be associated to the physical characteristics of the target that returned the echo, thus allowing for its unambiguous characterization. Means are discussed to extend the procedure, here illustrated with acoustics and sonar, to any active return from any type of sensor.