My friend Jerry Snyder just post his artiles:

If your contemplating starting a business or if you are the owner of a business, it is important you should understand the importance of computing business profitability.

With any business, no matter what goods or service is being provided, it is very important that the owner understand the business side of the business. The purpose of your company, business is to generate a profit.
Fixed Versus Variable Expenses

When computing business profitability, you will notice that your business has many different expenses. Some of these expenses are fixed and others are variable. Fixed expenses are expenses that you must pay no matter how much product you make. This is something you pay even if you do not open up your business for the month. Examples of fixed expenses are rent, employee expenses, and some utility costs.(...)

Sincerely
Mariusz Antonik
http://your-success-builder.com