What this site is for
This is patient education about skin that has been changed by a lifetime of light, published by Chongqing West District Hospital, a tertiary general hospital in Jiulongpo District, Chongqing. It is a concern guide rather than a procedure page: it answers why the skin looks like this, whether it needs treatment at all, and which of several paths applies. The peels, light devices and operations themselves, and the anatomy they work on, are explained on the skin hub and on the peel and laser pages, and repeating them here would help nobody.
The distinction the site is built on
Light does at least three different things to skin, and they are treated differently. The shorter wavelengths produce the burn, which is what a sunburning product is designed against. The longer wavelengths reach the connective tissue, where they produce the laxity and the deep textural change that no topical can touch. The visible part of the spectrum drives pigment, which matters most in darker skin tones. A person can therefore have stopped burning entirely and still be accumulating two of the three, which is why advice that only prevents burns is incomplete advice.
What it deliberately does not do
It does not name products, brands or ingredients in detail, quote prices or dosages, or state wavelengths. It does not describe any treatment as painless, scarless or risk-free, and it does not promise that any result will hold. It does not present a cream as an alternative to a procedure where a procedure is the honest answer, or a procedure as a substitute for examining a mark first. And it does not treat a changing mole, a spot that bleeds or a patch that fails to heal as an appearance problem at any point.
The limits of a website
Nothing here can tell you whether a particular mark on your skin is sun damage or something that needs to be removed. That requires someone to look at it with a lens, to compare it against the rest of your skin and against a record of how it looked before, and to ask about your history — observations that take minutes in person and cannot be made at all from a screen. Use this site to arrive at an assessment with better questions, and treat any answer you receive here as general information rather than as advice about you.