Which type of business structure is characterized by a single individual running the business and bearing unlimited liability?

A sole trader is a business structure where a single individual owns and runs the business. This structure is characterized by the simplicity of starting and managing the business, as there are minimal legal requirements. One of the key features of a sole trader is that the owner has unlimited liability, meaning that if the business incurs debts, the owner is personally responsible for repaying those debts. This personal liability can extend to the owner's personal assets, making it critical for potential sole traders to understand the risks involved.

In contrast, partnerships involve two or more individuals who share the responsibilities and profits of the business, while private limited companies and public limited companies are separate legal entities. The latter two structures provide limited liability, protecting the owners’ personal assets from business debts.