How do you explain cash flow?

Cash flow is the net amount of cash that a company has at any time, it is difference between money coming into a business minus money spent to keep the business running. It can be either positive or negative.

What are the 3 types of cash flows? What is a cash flow example? Does cash flow include salaries? What are the best cash flow businesses? How is cash flow calculated? Why is cash flow so important? What is considered a good cash flow?