Pollution is the introduction of contaminants into the natural environment that makes it unsafe or unsuitable. There are several types of pollution including land, water, air, noise, and light pollution. Land pollution results from household garbage and industrial waste filling up landfills. Water pollution occurs when chemicals, sewage, and farm runoff contaminate streams, lakes, and oceans. Air pollution involves particles and gases being released into the air from sources like burning fuels. Noise pollution affects health and comes from sources like planes and industry. Light pollution disrupts ecosystems and makes it difficult to see stars at night. Pollution has negative impacts that reflect the importance of avoiding contaminating the environment.