Citric acid is a natural preservative that exists in many different fruits, vegetables and other products. It can also serve as a ph adjuster, which makes it a great ingredient for personal care products, food coloring, and many other solutions.
Many products in the food and beverage industry also use citric acid to add to a sour taste. It is a common ingredient that chefs will use in many dishes, including an emulsifier for ice creams, ripening agents for mozzarella cheese, and much more. Home brewers have also been buying bulk citric acid for many years to modify their water when making beer or other beverages.
Of course, citric acid is also used outside the food and personal care industries. It is actually a common additive for concrete to slow settling time, making it easier to work with and manipulate before it sets up.