The term Stone Age refers to the prehistoric period before the advent of metal-working, when most tools were fashioned from rocks and stones. According to the Oxford Dictionary, the Stone Age lasted about 2.5 million years.
Stone Age people had not yet mastered the art of making tools from metal, so they had to rely on tools made from stones, animal bones or other natural objects. The end of the Stone Age is marked not only by the advent of metal work but also by the development of agriculture and the first towns. In Europe, the Stone Age was succeeded by the Bronze Age about 4,000 or 5,000 years ago.