The current trend to using short-pulse, high-peak power lasers has led to better temporal and spatial confinement of effects; however, a consequence of these techniques is the production of pressure transients in tissue which can propagate for long distances. The terminology that is used in the literature has been confusing since there is no absolute physical criteria for the classification of some of the phenomena. It is suggested that investigators use some practical approaches for choosing the descriptions of their systems. The four commonly observed pressure effects include shock waves, acoustic waves, mechanical effects, and radiation pressure. The distinction is usually made between mechanical effects (ex: cavitation) and radiation pressure (ex: optical trapping). The distinction between shock and acoustic transients is frequently blurred. Shock waves with rise times in the order of picoseconds should be distinguished from acoustic waves with rise times in the order of nanoseconds because there are unique characteristics to this type of pressure phenomena.