A pollutant is a substance or agent introduced into the environment that causes harm or discomfort to humans, other organisms, or ecosystems. Pollutants can be in the form of gases, liquids, or solids, and they can originate from various sources such as industrial activities, transportation, agriculture, and waste disposal. These substances can disrupt the natural balance of ecosystems, harm human health, and contribute to environmental degradation and climate change. Efforts to monitor, control, and reduce pollutants are crucial for safeguarding the environment and public health.