Citric acid is a natural acid that is found in many fruits.
In the food industry, it serves as a preservative, flavoring agent, and vegetable rinse. In personal care products, it's used to add an effervescent quality (e.g., bath bombs), to adjust pH, and to serve as an alpha hydroxy acid (e.g., anti-aging creams). You'll find it in shampoos, hair colorants, dyeing, antibacterial wipes, liquid hand soaps, body gels and washes, conditioners, eye pencils, deodorants, baby wipes, nail enamels, peels, creams, tanning, cleaning products, chelation etc. It's also used in some supplements and pharmaceuticals (e.g., vitamin powders, syrups, elixirs).