In the U.S., "gravel" typically refers to small, naturally rounded pieces of rock, usually 2-75mm in diameter, formed by weathering and water erosion. It is a common commercial product for construction and landscaping, especially for roads and driveways. While "gravel" can sometimes be used informally to describe any crushed stone of a certain size, true gravel is distinguished by its smooth, rounded edges, a result of natural transport by water.