What are the "stock and flow" variables?

Stock and flow variables are stocks that are measured at a certain period in time or over a longer time span, otherwise known as the flow factor, according to BusinessDictionary.com. About.com notes that a stock variable is a one-dimensional measurement, whereas a flow variable is a two-dimensional one.

About.com adds that stock variables are an immediate measurement of a stock at a specific moment in time. Stock variables are not always accurate over a long period of time, as the financial status of a company changes over time. Examples of common stock variables include cash, assets, land and accounts receivable.

About.com notes that one of the dimensional measurements of a flow variable is the time factor, and the other is the variable quantity that was calculated over a certain time frame. Flow variables are crucial measurements in auditing and accounting practices; they are normally calculated over the business quarter or calendar year. Some flow variables are calculated monthly.