In children’s book terms, a raster refers to a digital image that is composed of a grid of tiny, individual pixels. Each pixel has its own color and together they create a complete image. Rasters are commonly used in illustrations because they allow for detailed imagery and vibrant colors, which are essential in appealing to young readers. Unlike vector images that are based on paths and mathematical expressions, rasters lose quality when scaled up, making them crucial for fixed-size applications, especially in print.