What does high external costs mean?

High external costs refer to the negative effects or consequences of an economic activity that are not reflected in the market price of a good or service, often borne by third parties or society at large. Examples include pollution, health issues, and environmental degradation resulting from industrial production. These costs can lead to market failures, as producers and consumers do not account for the full societal impact of their actions. Addressing high external costs typically requires government intervention or regulation to internalize these costs, promoting more sustainable practices.