Clay is a type of soil or dirt that's made of very small particles. You can mold clay into different shapes when it's wet.
Clay is terrible for planting a vegetable garden, but it's perfect for making pottery, tiles, or bricks. You can shape damp clay into a bowl or a cup, and when it's dried and fired in a very hot oven, it becomes extremely hard and sturdy. The Old English root of clay is clæg, "stiff, sticky earth."