An anvil is a heavy block of iron or steel with a flat top surface where blacksmiths shape hot metal by hammering it. Picture a solid chunk of metal weighing 75 to 500 pounds, sitting on a sturdy stand in a forge. When a blacksmith heats iron in the fire until it glows orange, they pull it out with tongs and place it on the anvil. Then they strike it repeatedly with a hammer, and the anvil's massive weight absorbs each blow, allowing the blacksmith to bend, flatten, or shape the metal into tools, horseshoes, or weapons.

Anvils have a distinctive shape: a flat top surface for hammering, a pointed end called the horn for bending metal into curves, and often a small hole called the hardy hole where special tools fit in. The ringing sound of hammer on anvil has echoed through workshops for thousands of years. Before factories and machines, blacksmiths at their anvils created nearly every metal object people needed.

The word also appears in the phrase caught between a rock and a hard place, sometimes expressed as between the hammer and the anvil, meaning stuck between two difficult choices. In your body, a tiny bone in your ear is called the anvil because of its similar shape.