The small plate that you place under your drink to prevent dirtying the table is commonly called a coaster. Coasters are typically made of materials like cardboard, cork, wood, or various types of absorbent materials, and they serve to protect the table surface from moisture, condensation, and potential stains that could result from cold or hot drinks. Coasters come in various shapes, sizes, and designs and are a common feature in bars, restaurants, and homes to maintain cleanliness and preserve the condition of the table or furniture.