Coda waves are one of the most striking features recorded on seismograms, and their study has bloomed over the last 10 years. Scattering and attenuation of high-frequency seismic waves constitute key subjects in both theoretical and applied research in present-day seismology. However, the narrow relations among coda waves, scattering, and attenuation are not taken into account often enough, nor is an overall comprehension of these subjects always offered. Coda waves of local earthquakes can be considered as backscattered 5 to 5 waves, and the quality factor which accounts for their decay, Q c , expresses both absorption and scattering-attenuation effects. How scattering constructs coda waves and contributes to their attenuation is not completely understood; work now in progress will improve the understanding of scattering theory. This review describes coda waves in detail and discusses their relation to attenuation in the context of research on seismic-scattering problems. Care has been taken to explain the statistical models used to deal with the heterogeneities responsible for scattering. The important role played by observational data is also stressed. where r\ and f2 define the points at which a fluctuation is measured and the average is made over an ensemble of the random media. Initially, N(f') adopted Gaussian or exponential forms. In the latest studies Von Karman functions are preferred. correlation distance, a It expresses the separation for which fluctuations become uncorrelated in the statistical study. It is also called "inhomogeneity scale length". uniform random field, N(r) depends only on the difference r\-TI. isotropic random field, N(f'} depends only on the modulus of r\-f^. normal random field, N(r) has the form of a Gaussian curve N(f) = JV(f0)e-r2/°'a (2) wave parameter, D Ratio of the size of the first Fresnel zone to the scale length of inhomogeneities. It can be given by the expression: D=t (3) K0t* where K is the wave number. Uses the Born approximation r=R»A .