File is a small production tool, which is made of carbon tool steel T 12 or T 13 after heat treatment. Used for the micro-machining of metal, wood, leather and other surface layers.

The earliest documentary records in the world originated from Greek literature. According to records, the Crete civilization in Greece invented bronze file around 2000 BC, the earliest copper file was invented by the ancient Egyptians in 1300 BC, and the iron file was invented around 700 BC. It is recorded in the west that the ancient Romans used carburizing heat treatment technology to make files around A.D. 1 100, but it is believed that carburizing technology was widely used to process files in ancient China during the Qin and Han Dynasties around 200 BC.