A foundation brush is an essential makeup tool used to apply liquid or cream foundation evenly across the face. It helps create a smooth, flawless finish by blending the product into the skin without leaving streaks or uneven patches. Foundation brushes come in different shapes, such as flat, rounded, or buffing brushes, each designed for specific application techniques. Using a foundation brush can provide better coverage compared to using fingers, while also being more hygienic. Regular cleaning of the brush is important to maintain skin health and ensure the best makeup results.