What is a P&L statement, and how do you read one?

A profit and loss statement, also called an income statement, reports performance over a period rather than at a moment. It starts with revenue, subtracts cost of goods sold to give gross profit, subtracts operating expenses such as rent, salaries, marketing, and software to give operating income, then accounts for interest, taxes, depreciation, and anything unusual to arrive at net profit. Reading it as a funnel is the right instinct: each line tells you where money left between the top and the bottom.

Its limits matter as much as its contents. A P&L says nothing about your bank balance, because it records revenue when earned rather than received, which is why it must be read alongside a cash flow statement and a balance sheet. The balance sheet is the companion snapshot showing what you own and owe at a point in time. Depreciation appears on the P&L as an expense in periods when no cash moves at all, which is one reason a profitable-looking business can be short of money and a cash-generating business can show a small profit.

What to actually do with it. Compare periods rather than reading one alone, since a single month's figures are noise and the trend is signal. Express each line as a percentage of revenue, which makes comparison across periods and against industry benchmarks possible regardless of scale, and makes creeping overhead visible immediately. Watch for expense categories growing faster than revenue, which is the earliest reliable warning of margin erosion. And separate one-time items from recurring ones, because a quarter flattered by a single unusual sale or damaged by a single unusual cost tells you very little about the underlying business.