The business end...
Redbacks are common around Australia and have seen feral populations establish in a number of foreign countries, including New Zealand, Japan and the USA.
Able to live in an urban environment with ease, and tolerant of a wide range of climactic conditions and environment, they are also efficient and effective hunters, spinning a large, messy, sticky web that catches any insects, and small reptiles, that blunder into it. Their highly toxic venom finishes of the prey in short time. This also is dangerous to humans and there are a number of deaths from their bite on record. Despite this, they are largely non aggressive if you do not put a body part into their nest with eggsacks. Generally they just want to get away, and if they feel really threatened, curl up in a ball and play dead. So leaving them alone is the wisest and safest option.
There are a number of species in the genus Latrodectus, including the closely related to the Black widow, all of which need to be treated as dangerous to deadly.
The male of the species is tiny.