operating activities
Think of a juice stand. The cash you take in from selling juice, and the cash you pay out for oranges, cups, your helper's wages, and the electricity bill — that is the everyday, bread-and-butter money of the business. It is not about buying the stand itself or borrowing money; it is the cash churn of simply running the thing day to day. That everyday cash churn is what 'operating activities' captures.
On the cash flow statement, operating activities is the first and usually most important section. It collects the cash effects of the transactions that determine net income — cash received from customers, and cash paid to suppliers, employees, for rent, interest, and taxes. For example, if customers paid 100,000 and the stand paid out 70,000 for fruit, wages, and bills, its operating cash inflow is 30,000. This is the cash a business squeezes out of its core purpose, before it spends on growth or deals with its financing.
Analysts care most about this section because it shows whether the core business is self-sustaining. A healthy company should, over time, generate positive cash from operations — that is the engine. If operating cash is persistently negative while the company survives only by borrowing or selling assets, that is a warning sign. Note that under the usual rules interest paid and taxes paid sit here in operating activities, which sometimes surprises beginners who expect interest to be 'financing'.
A bakery collects 500,000 from customers, pays 200,000 for flour and ingredients, 180,000 in wages, 20,000 in interest, and 30,000 in taxes. Its net cash from operating activities is 500,000 − 200,000 − 180,000 − 20,000 − 30,000 = 70,000.
Cash in from customers, cash out to keep the doors open — that is operating cash flow.
Under US GAAP, interest and dividends received and interest paid are classified as operating; IFRS allows more choice (interest paid may be financing). So the same cash item can land in different sections depending on the rulebook.