Uncontrolled garbage dump
A landfill is a place where waste is kept. Waste is usually buried in landfills, but it may first be sorted to remove any recyclable materials.
Landfills have a bad smell and look bad, therefore are usually located far away from where people live.
Once the waste is crushed into very small pieces, it is buried, but in the absence of oxygen, a dangerous gas called methane is created. This process is called anaerobic digestion. In some countries, the methane from landfills is used to generate energy.