A small business may be defined as a business with a small number of employees. The legal definition of "small" often varies by country and industry, but is generally under 100 employees in the United States while under 50 employees in the European Union (In comparison, the American definition of mid-sized business by the number of employees is generally under 500 while 250 is for that of European Union). These businesses are normally privately owned corporations, partnerships, or sole proprietorships. In Australia, small business is defined as 1-19 employees and medium businesses are made up of 20-200 employees.

However, other methods are also used to classify small companies, such us annual sales (turnover), assets value or net profit (balance sheet), alone or in a mixed definition. These criteria are followed by the European Union, for instance (headcount, turnover and balance sheet totals).

Small businesses are common in many countries, depending on the economic system in operation. Typical examples include: convenience stores, other small shops (such as a bakery or delicatessen), hairdressers, tradesmen, solicitors, lawyers, accountants, restaurants, guest houses, photographers, small-scale manufacturing etc. Small businesses are usually independent.

The smallest businesses, often located in private homes, are called microbusinesses (term used by international organizations such as the World Bank and the International Finance Corporation) or SoHos. The term "mom and pop business" is a common colloquial expression for a single-family operated business with few (or no) employees other than the owners. When judged by the number of employees, the American and the European definitions are the same: under 10 employees.

Advantages of small business

A small business can be started at a very low cost and on a part-time basis. Small business is also well suited to internet marketing because it can be very manageable to serve a niche, something that would have been more difficult prior to the internet revolution which began in the late 1990s.

Adapting to change is crucial in business and particularly small business; not being tied to any bureaucratic inertia, it is typically easier to respond to the marketplace quickly. Small business proprietors tend to be intimate with their customers and clients resulting in greater accountability and responsiveness.

Independence, one survey of small business owners showed that 38% of those who left their jobs at other companies said their main reason for leaving was they wanted to be their own boss. Freedom to operate independetly is a reward for small business owners. Many people desire to make their own decisions, risks and being able to succeed and reap the rewards. However, independence does not come lightly. Entrepreneurs require to work very long hours and understand that the customer is, ultimately, the boss. They do though have the satisfaction of making their own decisions within the constraints imposed by economic and other environmental factors.