[en] Collisions in which two heavy ions come into close contact (touching) may be separated into three categories, namely Deep Inelastic Scattering, Quasi-Fission and Complete Fusion. The three processes are associated with the relaxation of the energy, the mass asymmetry and the shape degrees of freedom, respectively. Quasi-fission processes are characterized by a net mass flow from the heavy to the light reaction partner which takes place on a relatively short time scale. In lighter systems, the intermediate complex rotates several times during the quasi-fission process and final fragments show forward-backward symmetric angular distributions and symmetric mass distributions. In these cases, the quasifission process can be discerned only by a quantitative analysis of the angular anisotropies, which are sensitive to the shape of the intermediate system. In heavier systems, the intermediate complex rotates less than half a revolution during the process, and the reaction time may be determined from the angle of rotation. Studying the time dependence of the mass drift toward symmetry we find that it has the characteristics of an overdamped motion with a characteristic time constant of tausub(ch) = 3 x 10^-21 (sec) which appears to be independent of the scattering system. (author)