Colorful flat map with light and shadow refers to a two-dimensional map design that employs various shades of colors to depict relief and depth, creating a sense of three-dimensionality. This technique is commonly used in cartography and graphic design to make maps more visually appealing and easier to interpret. It involves the use of shadows and highlights to give the impression that the map's features are elevated or recessed, much like how light and shadow work in real life.