Companies are owned by shareholders. Each share is a proportion of the company, which the shareholder owns. Both public and proprietary companies may have as few as one member, but whereas a public company, such as BHP, will often have thousands, a proprietary company may have a maximum of 50 non-employee shareholders. All companies must have a director. Public companies must have at least three.
Directors are the management of the company.
In addition, every company must have at least one company secretary, who can also be a director. The Corporations Law has a number of replaceable rules which govern the internal management of a company. These rules apply usually automatically unless the company displaces or modifies them in its own constitution. Some of the replaceable rules are replaceable for proprietary companies but mandatory for public companies. Replaceable rules do not apply to a proprietary company while the same person is both its sole director and sole shareholder.