In the long run, all production factors are considered to be variable. This means that firms have enough time to adjust all of their inputs, including labor, capital, and technology, in response to changes in market conditions. In the short run, at least one input is considered to be fixed, usually capital. This is because capital, such as a factory or equipment, cannot be easily adjusted in the short term. However, in the long run, firms can make adjustments to all their inputs to optimize their production and minimize costs.