A Profit and loss statement  is a key reporting of your business
activities showing what its income and expenses are for a particular
time period in question.

Armed with this information you are better able to make business
decisions based on the numbers you see and the potential there may
be for improvement in the various areas involved.

This sort of an accounting report is easily generated on your personal
computer provided you are willing to maintain it with current information
of your business transactions. Its certainly cheaper than using a
book-keeper or accountant and will ensure you are able to keep up
with the changes in your business cycle - as they evolve.

Percentages shown below are in relation to total Sales Revenue
Except for Cost of goods sold section - where they are based 
on cost of sales within each category

Sample P & L (Operating Statement or Income statement)
Mom $ Pop TV & Stereo Retail store
Monthly Profit and Loss Statement for Month in Year
Monthly Sales
Stereo Equipment $40,000.00 65.79%
Television equipment $20,000.00 32.89%
accessories $800.00 1.32%
$60,800.00 100.00%
Cost of goods sold
Stereo Equipment $24,000.00 60.00%
Television equipment $17,000.00 85.00%
accessories $400.00 50.00%
$41,400.00 68.09%
Gross Profit $19,400.00 31.91%
Operating expenses
Salaries and commissions $6000 9.87%
Misc expenses $400 0.66%
Rent (with included utilities) $4000 35.91%
Advertising $600 0.99%
Phone expenses $80 0.13%
Computer lease $60 0.10%
Total expenses $11140 18.32%
Pre-tax profit $8,260.00 13.59%