Cash flow refers to the increase or decrease in the amount of cash available to a business, institution, or individual over a period of time. There are several types of cash flows that are important for financial analysis and running a business. Cash flow diagrams visually represent income and expenses over time using a horizontal line with markers indicating expenses and costs at different time intervals, usually at the end of the year. Certain cash flows like rent are handled differently by indicating them at the beginning of the period instead of the end.