Search this question and you'll find charts with eleven steps, colour-coded, with arrows. Most of it is invented.
Here are the two rules that actually change anything.
Rule one: thinnest to thickest
Watery things first, heavy things last. A serum can't push through a moisturiser, but a moisturiser sits happily over a serum.
That single principle sorts almost any routine without needing a chart. Toner before serum, serum before cream, cream before oil, oil before sunscreen. Not because of a rule you memorised, but because each is heavier than the last.
Rule two: sunscreen goes last, in the morning
It needs an even, unbroken film on the surface, and anything applied over the top disturbs it. So it's the final step, and you use more than feels reasonable.
That's the lot. Everything else is preference.
What doesn't matter as much as you've been told
Waiting between layers. Thirty seconds to a minute, so you're not dragging a wet layer around. The fifteen-minute waits you'll read about are not doing what people think.
Morning versus evening for most actives. With the exception of retinol, which is genuinely better at night, and sunscreen, which is obviously a daytime affair, timing is mostly about what you'll remember to do.
The number of steps. A four-step routine done consistently outperforms a ten-step routine done when you can be bothered. Every extra step is another chance to skip the whole thing.
A routine that will do most of the work
Morning: rinse or gentle cleanse, serum, moisturiser, sunscreen.
Evening: cleanse properly, serum, moisturiser. Light therapy after the serum if you use it.
Four things and four things. If you want to add something, add it for a reason you can articulate, and give it three months before deciding whether it earned the shelf space.
The uncomfortable maths
The skincare industry's growth depends on people owning more products, not on people having better skin. Those two things overlap sometimes. They are not the same thing.
We sell skincare. We'd still rather you owned three things you use than nine you don't.
General information, not personal advice.