Microeconomics production and consumption/Short run

"Our analysis of production and cost begins with a period economists call the short run....

"At any one time, a firm will be making both short-run and long-run choices. The managers may be planning what to do for the next few weeks and for the next few years.

"Their decisions over the next few weeks are likely to be short-run choices. Decisions that will affect operations over the next few years may be long-run choices, in which managers can consider changing every aspect of their operations. Our analysis in this section focuses on the short run." - Principles of Microeconomics