efficient

Efficiency is a measure of how effectively a system uses resources to achieve a desired output. It is commonly defined as the ratio of useful output to total input, often expressed as a percentage. The concept applies across fields such as physics, engineering, economics, and information technology, and it generally implies minimizing waste, delay, or energy loss while maintaining the intended result.

In economics, efficiency has several dimensions. Technical efficiency means producing the maximum possible output from a given set of inputs. Allocative efficiency occurs when resources are distributed to reflect consumer preferences, maximizing social welfare. Dynamic efficiency refers to long-term gains from innovation and investment in capital, skills, or technology.

In physical sciences and engineering, efficiency describes how much of the input energy or work is converted into useful output. For heat engines, thermal efficiency is the ratio of work produced to heat supplied, with theoretical limits such as the Carnot efficiency governing maximum possible performance for a given temperature difference. In computing and information technology, algorithmic or process efficiency relates to how quickly or with how few resources an algorithm or system completes a task.

Measuring efficiency requires context and baselines, and improvements often involve optimization, better design, or advanced technologies. It is important to distinguish efficiency from effectiveness: a highly efficient process may still fail to achieve the intended goal if its outputs are misdirected or misaligned with objectives.