Hand tools have been used by humans since the Stone Age when stones were used for hammering and cutting. During the Bronze Age tools were made by casting the copper and tin alloys. Bronze tools were sharper and harder than those made of stone. During the Iron Age iron replaced bronze, and tools became even stronger and more durable. The Romans developed tools during this period which are similar to those being produced today. In the period since the industrial revolution, the manufacture of tools has transitioned from being craftsman made to being factory produced.