So what is a the most useful definition of a small business?
Revenue and numbers of staff are commonly used. Whilst these are useful indicators, they can also vary significantly, leaving a large grey area between 'small' and 'medium' businesses.
As a business consultant that specialises in small business, the definition that I work by is:
The owner of the small business has an active responsibility for the management of core business functions. There is very limited (often no) employment of specialised skills to manage such functions as marketing, financial management, HR, sales or business planning / strategy.
What are your opinions or definitions?
Dr Warren Harmer, Director, Crecer