Environmental indicators are measurable factors that provide information about the state of the environment. They help scientists and policymakers assess the health of ecosystems, track changes over time, and identify potential problems. Common indicators include air quality, water quality, biodiversity, and greenhouse gas emissions. These indicators can be used to evaluate the effectiveness of environmental policies and initiatives. For example, improvements in air quality can indicate successful regulations, while declining biodiversity may signal habitat loss. By monitoring these indicators, we can better understand our impact on the planet and make informed decisions for a sustainable future.