Flat brushes are painting tools characterized by their wide, rectangular bristles. They are commonly used in various art forms, including acrylic painting, watercolor painting, and oil painting. The flat shape allows for broad strokes, filling large areas quickly, and creating sharp lines or edges. These brushes come in different sizes, making them versatile for both detailed work and larger canvases. Artists often use flat brushes for techniques like blending, washing, and scumbling. Their design helps achieve smooth, even coverage, making them a staple in many artists' toolkits.