Whether you are running a business or managing the household finances, cash flow is critical.
The difference between cash coming in and cash going out in any given period of time is the net cash flow. If it is positive, your cash balances will increase and if it is negative, your cash balances will decrease.
The easiest way to grasp the concept of cash flow is to think of a water tank. Imagine a pipe at the top of the tank bringing water in from an external water supply. At the bottom of the tank, imagine a pipe taking out water to be used for a multitude of purposes.
The water in the tank will rise and fall depending on whether more water is coming in than going out.
Cash flow is easy to manage when the flows are constant. It is not so easy when there are large variations in cash flows, for example, in small or expanding businesses, in households where income comes from self-employment or from commission, and in property investment. Without careful management the tank can run dry, with disastrous consequences.