Tech levels 0 - 4.

Despite being designated as Technology Zero, this tech level represents probably the widest range of technological achievements on the entire scale - from chimpanzees bashing rocks together, to complex agriculture, cities and social civilisations. It also represents no technology at all - a barren world completely devoid of life is also defined as TL 0, though in practise there is considered a difference between no technology and TL 0.

The principle defining characteristic of a TL 0 society is that it has not figured out how to process metals. There is a difference between processing and using metals. Gold is often discovered quite early, and used as jewellery or a form of currency, but actually refining and processing metals is considered the domain of TL 1 and above.

The earliest stage of a TL 0 society once it has discovered basic tool use. Entirely based on hunter/gatherer societies, tools tend to be of wood, stone or bone.

Domestication of animals.

Farming.

Trade with TL 0 civilisations is rarely worthwhile, for not only do they lack any concept of what they want, they have little to offer. Pretty much anything that the can produce themselves is both readily available on other worlds, and of such poor quality that no-one else wants it.

However, there are many goods which a TL 0 society would find useful, from basic medicines, synthetic clothing and artistic items to metal tools and weapons. Neolithic societies may be interested in firearms, and will quickly learn how to use them, though will be unable to manufacture their own.

Most TL 0 worlds are useful as sources of raw materials - wood, animal products and mineral deposits can be easily strip mined since any natives will not be able to object.