A raster image, also known as a bitmap, is a type of digital image that is composed of a matrix of individual pixels. Each pixel has its own color and together, they form an image. Raster images are commonly used in children's books for illustrations and graphics, as they can produce detailed and colorful visuals. However, they can lose quality if resized significantly, which makes them distinct from vector images, which maintain their quality regardless of scaling. Understanding raster images is essential for graphic design and illustrations in the world of children's literature.