There are many definitions for small businesses.

• For some it depends on the number of employees.
• For others it is about the gross income generated.

For the sake of this discussion a small business here can be a start-up, a one man shop or a company with many employees, however it cannot be part of from a franchise.
The comparative traits of these businesses are the following:

• budget is limited and even practically not existing
• time is a precious commodity to manage carefully
• there is an entrepreneurial spirit live and kicking in the company.

Budget:

Funds can be available. They can come from a small loan, credit cards, or personal equity. But it is a far cry from wealthy businesses that can allocate a significant budget aside for the need of the project including staff, consultants, suppliers and new software and equipments.

Time:

A precious commodity. Yes a small business owner can spend his evenings and weekends to run his company and most of the time do so. Dedicated 'employee' volunteers may also invest in that business with their own time.  But systematically relying on that extra time is a fallacy. If such time is to be used then it has to be for the right reasons.

• Entrepreneurial Spirit
  The business has not reached a point where people roles are not fungibles and every task relies on specialized workforce. Indeed, the entrepreneur will most likely do it himself, find a way and solve the problem somehow.
• If this sounds like the place where you work then this information is for you.