What period is characterized by at least one factor of production being fixed?

The short run is characterized by at least one factor of production being fixed, which distinguishes it from the long run where all factors can be varied. In the short run, businesses cannot change certain inputs, such as capital (factories, machinery, etc.), while they can adjust variable inputs like labor and raw materials to respond to changing market conditions. This fixed factor limits the ability of firms to fully adjust their production levels in response to changes in demand or costs. Because of this rigidity, the short run often leads to concepts like diminishing returns, where adding more variable inputs to a fixed resource can lead to less efficient production outcomes. Understanding this distinction is crucial for analyzing production decisions and cost structures in economics.