Underpainting is a technique used in painting where an initial layer of paint is applied to a canvas before the final layers. This base layer often consists of a monochromatic color or a simple color palette, which helps to establish the composition, values, and overall mood of the artwork. Artists use underpainting to create depth and to guide the application of subsequent layers. The underpainting serves as a foundation for the final details and colors, allowing artists to build complexity in their work. This method is commonly used in oil painting, but can also be applied in other mediums. Famous artists like Vincent van Gogh and Rembrandt utilized underpainting to enhance their masterpieces.