A landfill liner is a protective barrier used at the bottom and sides of a landfill to prevent harmful substances from leaking into the surrounding soil and groundwater. Typically made from materials like high-density polyethylene (HDPE) or clay, these liners help contain waste and minimize environmental impact. The primary purpose of a landfill liner is to safeguard the environment by isolating waste materials. This is crucial for preventing contamination, as landfills can produce leachate, a toxic liquid formed when rainwater filters through waste. Properly designed liners are essential for modern waste management practices.