Underglazing is a pottery technique used to apply color or designs to clay before it is glazed. This method involves using a colored slip, which is a liquid mixture of clay and water, to create patterns or images on the surface of the pottery. Once the underglaze is applied, the piece is fired in a kiln, allowing the colors to bond with the clay. After the initial firing, a clear glaze can be applied over the underglaze to enhance the colors and provide a glossy finish. This process not only protects the artwork but also adds depth and vibrancy to the final piece, making it visually appealing.