Protein shakes are beverages made by mixing protein powder with water, milk, or other liquids. They are often consumed by athletes and fitness enthusiasts to help build muscle, recover after workouts, or supplement their daily protein intake. Common sources of protein in these shakes include whey, casein, soy, and pea protein. These shakes can also include additional ingredients like fruits, vegetables, or healthy fats to enhance their nutritional value. Many people enjoy protein shakes as a quick and convenient meal replacement or snack, making them popular among those with busy lifestyles or specific dietary goals.