Lithography is based on the principle that oil and water repel each other. An image is drawn onto a smooth stone or metal plate using a grease-based medium, and the plate is then treated with a chemical solution. The drawn areas retain ink, while the non-image areas attract water and repel ink. Ink is applied, and the plate is pressed onto paper to transfer the image. Lithography allows for fine details, tonal variations, and textures, making it popular for both artistic prints and commercial work like posters and book illustrations.