Short answers, pulled from the story.
Prehistory is the period of human history between the first known use of stone tools by hominins, around 3.3 million years ago, and the beginning of recorded history with the invention of writing systems. It is also called pre-literary history. It can be known only from material archaeological and anthropological evidence, because there are no written records from it.
Prehistory ended at different times in different places, because the adoption of writing was a slow global process. The earliest known writing systems appeared around 5,200 years ago. In Egypt prehistory ended around 3100 BCE, in New Guinea it ended in the 1870s, and in Australia 1788 is usually taken as the end.
The three-age system divides human prehistory into the Stone Age, the Bronze Age, and the Iron Age, named for their predominant tool-making technologies. In some areas a transition period called the Chalcolithic or Copper Age sits between the Stone Age and Bronze Age. The system remains in use for much of Eurasia and North Africa.
Researchers study prehistory mainly through the archaeological record, using excavation, geologic and geographic surveys, and scientific analysis. The key step is dating, and the most common technique is radiocarbon dating. Population geneticists, historical linguists, and disciplines such as paleontology, palynology, and molecular genetics also contribute evidence.
Prehistory is anonymous because it is restricted to material processes, remains, and artefacts rather than written records. It deals with the activities of archaeological cultures rather than named nations or individuals. Terms such as Neanderthal or Iron Age are modern labels whose definitions are sometimes subject to debate.
The Stone Age lasted for roughly 3.4 million years and encompasses 99 percent of human history. It begins with the first use of stone tools by hominins around 3.3 million years ago, with the oldest tools found at the Lomekwi site in Kenya. It ended between 4000 BC and 2000 BC with the advent of metalworking.
The oldest securely dated evidence of copper making at high temperature was found at an archaeological site in Serbia, dating from 7,500 years ago. The find, made in 2010, extended the known record of copper smelting by about 800 years. It suggested copper smelting may have been invented independently in separate parts of Asia and Europe.