Screen printing is a technique where ink is applied to a substrate through a mesh screen that has been prepared with a stencil of the desired design. Each color in the design requires a separate screen, and the ink is pushed through the mesh onto the material using a squeegee. This method is widely used for producing vibrant and long-lasting prints on textiles, posters, and other surfaces. It's particularly cost-effective for large orders due to the efficiency of the process once the screens are created.