A business is defined by the US Congress as a legally registered company or unincorporated partnership, unincorporated joint stock company, or corporation having one or more specified classes of equity or property and operating for the benefit of all members of the class. A business may be a sole proprietorship, partnership, or corporation. Many businesses are publicly held companies with one or more shareholders. Private companies are generally less public than publicly held business enterprises.

Businesses can be organized in many ways, most common being a sole proprietorship, partnership, corporation, and limited liability partnership (LLP). Sole proprietorships are owned and operated by the individual who is the sole owner. Partnerships are owned and operated by parties or groups of people. Each member of a corporation is a share holder in the ownership of the corporation. In a sole proprietorship, all the partners are owners; in a partnership, the partners are termed the partners in the partnership; and in an LLC, the owners are termed the owners in the LLC.

Businesses are usually run by an individual. This person may be a sole proprietor, a partnership, an owner in a corporation, or an employee. A business must be registered with the government in order to operate legally. All businesses must file a complete annual and quarterly return with the IRS. Individuals working in businesses must comply with all local, state, and federal laws regulating businesses and individuals working in businesses.