Here’s the truth about serum: It’s the biggest secret to having younger-looking, radiant skin.

You know all the other steps to staying healthy—and showing it: wearing SPF, and applying retinol. You stay hydrated and eat healthy foods. You get lots of exercise and plenty of sleep. But, are you applying serums? They can give your skin some of the most immediate and impactful benefits.

Serum seeps into all three layers of your skin to work its magic at deeper levels than moisturizer ever could. Those moisturizing creams merely sit atop your skin. They’re equally important, and shield skin from toxins, but they do little to reverse dark spots and smooth wrinkles. Serums, on the other hand, can correct hyperpigmentation and puffy eyes.

Serum brightens your skin complexion, and can preserve moisture levels in ways that moisturizers never could (funny, given its name). No two serums are alike in terms of ingredients and overall benefits, but almost all of them brighten your skin and smooth complexion. Here are eight of our favorite serums; apply them to clean, dried skin before moisturizers, SPFs, retinol or night creams.

Dr. Dennis Gross C+ Collagen Brighten & Firm Vitamin C Serum

Courtesy Dr. Dennis Gross Skincare

Best Overall Serum

Vitamin C is one of the best ingredients you can apply to skin for brighter, more even complexion. Dr. Dennis Gross Skincare's serum is packed with it, along with collagen amino acids, for an instant pick-me-up for tired or dull skin. Use it daily to preserve a fresh face, and to get ahead of the inevitable hangovers or early mornings.

Buy Now: $78

More Great Options

SkinCeuticals Corrective Gel Serum

If your skin suffers from redness or discoloration, then look for a corrective serum. SkinCeuticals’ gel serum uses thyme and cucumber extract to soothe irritation, as well as mulberry extract to even skin tone and gently hydrate the skin. If most moisturizers make your skin break out, then this is a gentle and top-notch moisturizing alternative.

Buy Now: $67

Aesop Parsley Seed Anti-Oxidant Serum

Courtesy Aesop

The biggest culprit in the aging process is oxidation, the chemical process that leads to cell breakdown. Thankfully, we can combat this with a host antioxidants which block that chain reaction and hold on to youthful skin for longer. Aesop's serum is pumped with ingredients rich in antioxidants like grape seed and panthenol and helps soothe and nourish skin with aloe.

Buy Now: $75

Perricone MD Eyelid Lift Serum

Courtesy Perricone MD

The skin around your eyes is more sensitive than the rest of your face, and is much thinner, too — hence why you quickly show signs of tiredness. (It’s fluid buildup from a lack of rest, shining through your skin.) So, target the eyes with a special-blend serum that tightens and brightens at the same time. In Perricone MD's eye serum, Vitamin F restores the skin's natural moisture barrier and elasticity, bouncing back your low-slung tired eyes (and alert eyes, if you’re plenty rested already — everyone benefits). It also prevents and helps reverse fine lines and other signs of aging.

Buy Now: $120

Brickell Night Serum

Some serums are best worn during the day — those that focus on hydration and pure brightening. Others, like corrective and exfoliating serums, are often best suited for bedtime so that they can sync with your body’s circadian rhythm to boost cellular turnover (and in turn guarantee that you wake up looking rested and more youthful). However, some serums cover both bases: Brickell’s night serum is ultra-hydrating — so much so that its impact is maximized by wearing it overnight. It’s loaded with plant stem cells, hyaluronic acid and vitamin C, and promises to magnify the benefits of a full night’s sleep. Your friends and colleagues will notice the difference within days. (Assuming you aren’t pairing it with a lovely binge-drinking or chain-smoking habit.)

Buy Now: $75

Herbivore Exfoliating Serum

There’s an entire family of serums that focuses on exfoliation, by using ingredients that dissolve dead skin cells and reduce hyperpigmentation (dark spots and discoloration). Herbivore’s serum does so with alpha- and beta-hydroxy acids, all of which are naturally derived, despite their sciencey-sounding names. They’re extracted from things like willow bark and sugar maple, and in turn leave skin bright, while minimizing pore size and smoothing skin texture.

Buy Now: $54

Caudalie Radiance Serum

It’s hard to categorize Caudelie’s skin-brightening serum, since it uses the brand’s proprietary blend of ingredients (Viniferine, derived from grape vines) — but they seem to deliver on their promise to brighten skin “62 times better than Vitamin C”. All around the globe, this is what Caudelie’s spa customers pay top dollar for, and you can enjoy the same complexion-smoothing effects for less than a buck a day (assuming you just use a couple drops daily).

Buy Now: $79

Anthony High Performance Anti-Wrinkle Glycolic Peptide Serum

Courtesy Mr Porter

If your skin texture needs attention just as much as your skin tone, then look for a corrective and smoothing serum. This one from Anthony is pumped with peptides, and it waxes poetic on your skin to undo signs of aging (like the appearance of fine lines, wrinkles, dark spots and acne spots). It also helps skin retain moisture thanks to the inclusion of algae extract, ensuring firmness and brightness.

Buy Now: $55