Metals are materials that are typically hard, opaque, shiny and good conductors of heat and electricity. They have properties such as malleability, ductility, hardness, metallic luster, and high melting points and densities. Some key properties include being able to be hammered into thin sheets or drawn into thin wires. Metals also produce sound when tapped and are generally solid at room temperature, except for mercury. They are essential materials used across many industries and applications.