Photo: Richard Phibbs for Harper’s Bazaar

I know you already know about retinol. I know you’ve seen it in drugstores, heard about it on TV, and listened to your best friend gush about it every time she “re-discovers” skincar. But do you really know what retinol does? Do you really know why you’re supposed to use it, or why most dermatologists consider it pure magic? Do you even really know how to apply it?

I’m going to go ahead and guess your answers are a resounding, “Umm, kind of? Not really? No?” And hey, that’s fine. Because I’m here to break down everything you’ve ever wanted—and never knew you wanted—to know about retinol, so you can reap all of its smoothing, brightening, firming, and zit-killing benefits fast, without hardcore irritating your skin.

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FACT #1: Retinol slows down your body’s aging process.

Up until your early-30s, your cells turn over every 28 days, creating a fresh layer of untouched, pristine skin,” says dermatologist Mona Gohara, M.D., associate clinical professor at Yale University. “But after you hit your mid-30s, your cell regeneration slows down, turning over every 50, 60, or 70 days.” And that slower cell regeneration is what causes your face to look dry, dull, and wrinkled. So, you know, the very picture of aging.

Retinol, however, sinks into your skin and speeds up cell turnover, causing your body to churn out fresher, smoother skin again, says Dr. Gohara. It essentially tricks your body into thinking it’s younger than it is, effectively creating a real-life Benjamin Button scenario. Granted, you won’t see results overnight—it’ll take at least three months of consistent nightly use to notice some reduction in fine lines, dark spots, and acne—but you will see young Brad Pitt–level results eventually.

FACT #2: Not all retinols are the same.

Technically, retinol is just one of the many different types of retinoids (the umbrella term for all vitamin-A derivatives, including retinol) that are on the market. A drugstore anti-aging formula, for example, could contain retinyl palmitate (the weakest of the retinoids), or it could contain retinol (the next strongest and most tolerable), retinaldehyde (even stronger), or adapalene (the strongest over-the-counter option that’s also specifically formulated to treat acne). Or, you could ask your dermatologist to prescribe you even stronger retinoids, like tretinoin or tazarotene, which work faster and more effectively, but can also be extra irritating.

So which retinoid to choose? Ideally, you’d have your derm walk you through the best option for your skin type. But since you’ll probably never make the appointment, Dr. Gohara suggests starting with the gentlest of retinoids, like retinyl palmitate (for sensitive or dry skin) or retinol (for all other skin types), moving up to a higher strength formula only after a year. Yes, year.

Regardless of which retinoid you choose, though, know that they’re all effective in the long run. Studies show that you’ll reap the same long-term anti-aging effects over time with a low-strength retinoid as you would with a moderate-strength retinoid, so don’t feel like using a “weak” retinol won’t do anything.

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FACT #3: Retinoids don’t have to be irritating.

Because retinoids cause skin to shed cells faster than normal, you’ll likely experience a few weeks of flakiness, dryness, irritation, and/or breakouts, until your skin gets through the adjustment period. Luckily, there are things you can do to mitigate the effects.

First, choose the gentlest formula (again, retinyl palmitate or retinol), and start slowly—apply it just one night a week for one week, two nights a week for two weeks, three nights a week for three weeks, and then every other night (for sensitive skin) or every night (for “tough” skin) indefinitely. “You have to use these products most nights of the week to get long-term benefits,” says dermatologist Tobechi Ebede, M.D., clinical assistant professor in dermatology at Cornell. “They are changing your skin, and if you don’t use them routinely, your skin will go right back to baseline.”

Still, that doesn’t mean you should load up on retinol to speed up the process—you’ll only end up burning off your face. Instead, use just the tiniest amount on clean, dry skin at night. If your retinoid is a night cream (usually in a jar), use just enough to cover your face in a sheer layer of cream. If your retinoid is a serum (usually in a pump bottle or tube) or a prescription, apply a pea-size drop over the entire face, wait 20 minutes for it to absorb, and then apply your usual serums and moisturizers on top of it.

Just make sure to use your acne-fighting products (i.e. anything that includes benzoyl peroxides or salicylic acid) on the nights you don’t use a retinoid, unless you want to play fast and loose with irritation. Don’t worry—retinoids inherently fight breakouts and oily skin, so you won’t suddenly turn into one giant zit.

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FACT #4: Retinoids don’t just help with wrinkles.

Sure, retinoids are the gold standard in wrinkle-preventing and line-smoothing treatments, but they’re also excellent at turning your face into a bright little marble. “Because retinoids stimulate cell turnover, which increases collagen and elastin production, they’ll also help plump up your skin, clear and shrink pores, and fade dark spots and redness,” says Dr. Ebede. MVP of skincare, am I right?

And we’re not just talking a little bit of improvement, either. Because retinoids work on a cellular level, not just a topical level like most skincare products do, they’re able to deeply resurface your skin, which can completely transform your complexion over time. I mean, just look at this Retin-A–using grandma who went viral for looking so young, or this acne-prone woman who broke the internet after completely clearing her breakouts with retinolRetinoids really are the key to perfect-looking skin.

Are you now effectively pumped and ready to use a retinoid? Are you about to make a dermatologist’s appointment or run to the skincare aisle of the drugstore? Has your mind been blown? I’m choosing to believe that your answers this time are one big “YUP.”

This article originally appeared on Marie Claire