The article discusses different models of technical change, focusing on how technology evolves in both single and multiple output scenarios. It looks at how technical change affects production, costs, and profits, and explores approaches that are either general or specific to certain inputs. The researchers examine time-driven technical change models and discuss how technical inefficiency can impact these models. They also explore the relationship between technical change and total factor productivity, considering both good and bad outputs. Overall, the article connects changes in total factor productivity with changes in profitability.