A drain trap is a plumbing device designed to prevent sewer gases from entering a building while allowing wastewater to flow through. It typically consists of a curved section of pipe that holds a small amount of water, creating a seal. This water barrier blocks harmful odors and gases from the sewer system. Commonly found in sinks, showers, and toilets, drain traps are essential for maintaining indoor air quality. They can become clogged with debris, leading to slow drainage or backups. Regular maintenance, such as cleaning or inspecting the drainage system, helps ensure they function properly.