The movement of money in and out of a business over a period of time.
For example, a landscaping company invoices $30,000 in May but receives $25,000 in payments while paying out $22,000 in expenses — resulting in $3,000 of positive cash flow for the month, even though $5,000 in receivables hasn't arrived yet.
Why it matters: It is the lifeblood of any business; even a profitable company can fail if it runs out of cash to pay its immediate obligations.