This document discusses company structure and types in Australia. It outlines the main structures as private companies, public companies, companies limited by guarantee, no liability companies, and unlimited companies. Private companies have restrictions on share transfers and member numbers, while public companies can raise capital from public share offerings. Companies limited by guarantee are non-profit organizations. It also compares differences between large and small companies based on staff and revenue criteria. Finally, it discusses the role of regulatory bodies in standardizing company regulations in Australia.