The most basic peel, easy to build up in strength.
A small-molecule acid is applied to loosen the bonds in the dead-skin layer so it sheds. With that build-up cleared, tone brightens, pores block less, and skincare absorbs better. Strength varies with concentration, so it usually starts low and works up.
It is done five or more times at one to two week intervals. Tone brightens over two to four weeks, and the concentration is raised step by step from a low starting point. Starting high raises the irritation and can leave pigment instead, so the level is increased as the skin adapts.