Gesso is a white paint mixture used as a primer for surfaces like canvas, wood, or paper. It creates a smooth, even base that helps paint adhere better and enhances the vibrancy of colors. Traditionally made from a combination of chalk, gypsum, and a binder, gesso can be applied in multiple layers to achieve the desired texture. Artists often use gesso before starting their paintings, as it prepares the surface for various mediums, including acrylic and oil paint. It can also be tinted with color to create a unique background. Overall, gesso is an essential tool in the art-making process.