Small businesses are types of corporations, partnerships, or sole proprietorships which have a small number of employees and/or less annual revenue than a regular-sized business or corporation. Businesses are defined as "small" in terms of being able to apply for government support and qualify for preferential tax policy. The qualifications vary depending on the country and industry. Small businesses range from fifteen employees under the Australian Fair Work Act 2009, fifty employees according to the definition used by the European Union, and fewer than five hundred employees to qualify for many U.S. Small Business Administration programs. While small businesses can be classified according to other methods, such as annual revenues, shipments, sales, assets, annual gross, net revenue, net profits, the number of employees is one of the most widely used measures.

A corporation is an organization—usually a group of people or a company—authorized by the state to act as a single entity and recognized as such in law for certain purposes. Early incorporated entities were established by charter. Most jurisdictions now allow the creation of new corporations through registration. Corporations come in many different types but are usually divided by the law of the jurisdiction where they are chartered based on two aspects: whether they can issue stock, or whether they are formed to make a profit. Depending on the number of owners, a corporation can be classified as aggregate or sole.