Today is Vitamin C Day.

SkinCeuticals (makers of the widely acclaimed C E Ferulic) recognized April 4 as National Vitamin C Day and Registrar at National Day Calendar proclaimed the day now be observed annually.

I am so happy because I love vitamin C so incredibly much but before we go into that, let’s begin with why it’s so great.

Vitamin C is an antioxidant.

Skin care, like any industry that makes money, is a lot of marketing and buzzwords. But there are real things that can do amazing things for our skin. Antioxidants are one of them.

The air is filled with free radicals, which are molecules that come from everything from the sun’s rays, pollution and cigarette smoke to blue light, like that from our smartphones and other screens we sit in front of.

Free radicals are unstable atoms. If you think back to high school chemistry, unstable atoms mean its outer shell is not full. These unstable atoms want to bond with other atoms, using the new atom’s electrons to fill its shell.

When free radicals are in the air, its basically a search-and-destroy mission: they seek the molecules in your skin to bond to. Too much of this bonding causes “oxidative stress” in skin which leads to dark spots, dullness and wrinkles and even skin damage. Unfairly and like everything else, it becomes even harder to fight the effects of free radicals as we age.

That’s where antioxidants come in.

Antioxidants prevent the effects of free radicals by giving up an electron to the free radical, which stabilizes it and lessens the chances it will damage your skin.

Every person should have vitamin C in their skin care. It’s an essential antioxidant and one of the most widely available. It also fades dark spots and boosts collagen production. Look for products with tetrahexyldecyl ascorbate, or THD, L-ascorbic acid and ester-C, but most products will just note they contain vitamin C.

One thing to be cautious of: Vitamin C is extremely and inherently unstable and the more it’s exposed to air or light, the less potent it becomes. You want to find a vitamin C with air-tight packaging (so try to avoid jars or, cleansers that you’re rinsing down the drain for that matter) or in a dark bottle. You also should store it in a cool, dark, dry place.

Tatcha Violet-C Brightening Serum is my new holy grail and has great packaging to preserve the integrity of the serum. Drunk Elephant C-Firma Day Serum is the same way. These options are pricey but you’re paying for potency and packaging. Vitamin C that works doesn’t leave a ton of room for bargain hunting but Mad Hippie Vitamin C Serum is a great affordable find. You also can go a different route with Vitamin C powders or capsules since they offer more stability. The Ordinary Vitamin C Suspension 23% + HA Spheres 2% contains tiny balls of vitamin C that burst when applied to skin. It feels gritty and not very luxurious but it’s an affordable option at $5.80. Vitamin C also comes in the form of eye cream (Drunk Elephant C-Tango Multivitamin Eye Cream) or in masks (Murad Intensive-C Radiance Peel.)

No matter your preference, there’s a vitamin C for you. So let’s celebrate this skin care powerhouse.