Oxidation is a word we don’t often think about related to skin.. Pennies, bike frames, and other metal compounds is typically what we think of. Well skin oxidizes too which is why we have antioxidant ingredients. The definition of skin oxidation is when a compound loses electrons because the level of oxides is increased; this is exactly why when oxygen combines with iron, you see rust [like on your bike frame]. Another case comes when sebum on the surface of the skin (a combination of keratin and oil) clogs pores and is exposed to the air. The result is a blackhead. 
Unfortunately, blackheads are not the only result of oxidation. Research has shown that skin oxidation is a massive contributor to photo-aging. As we get older, our skin is more and more exposed to the elements + UV irradiation causing our skin to lose elasticity, increasing the development of fine lines and wrinkles. Our skin begins to essentially lose the ability to “bounce back.”
Antioxidants help correct and prevent signs of aging, prevent sunburn, help skin repair itself by promoting collagen production, brighten the complexion, and prevent skin cancer since some have anti-carcinogenic properties. Products that are high in antioxidants can really help combat this. Ingredients such as Vitamin A, Vitamin B, Vitamin C, Vitamin E, Niacinamide, fruit seed oils and extracts such as tomato/pomegranate/raspberry/passionfruit, glutathione, flavonoids, and polyphenols, are some of the top antioxidant ingredients. There are several more but this is a great list to reference. Also, you don’t need all of them to see results but if you are using products formulated for anti-aging- aka Thyrst Beauty :) - that include several of these you are in good shape. The exact plan of action for each individual should be determined based on how much photo-aging you are experiencing but, as a benchmark, this is how you want to approach at the very least preventative measures.