Whey protein is a type of protein found in milk. It is produced while making cheese, and it can be isolated from this process to create high-quality whey protein powder. At its most basic level, whey protein powder is created by filtering and purifying the liquid component of milk. This process removes lactose and fat from the liquid, leaving behind a concentrated form of protein that can be dried into a fine powder. Depending on the desired protein concentration in the final product, this process goes through several rounds of filtration and drying. Once the desired protein level is reached, the powder can be flavored and packaged for sale. Whey protein powder is popular among athletes and bodybuilders because it contains the essential amino acids needed for muscle growth and recovery.