What Has Changed? The main change in this update is how professional peeling agents are classified and organised. In the previous manual, many acids were taught as individual “types of peels”. In the updated structure, we now separate core professional peeling agents from other important acids that are more commonly encountered within multi-acid formulations, as well as from supporting ingredients that may be present in peel products but are not themselves primary peeling agents. This does not mean that what you previously learned is no longer valid; rather, the information has been refined to better reflect how modern professional peels are actually formulated and used in practice. You will therefore notice that some acids are now discussed in a different category rather than being presented alongside the main stand-alone peel types. The updated framework also places greater emphasis on understanding the complete formulation, pH, buffering, vehicle, application protocol and client response, rather than judging a peel only by the acid name or percentage.