A P-trap is a plumbing device that prevents sewer gases from entering a building. It is shaped like the letter "P" and is typically found under sinks, bathtubs, and other fixtures. The curved section of the trap holds a small amount of water, which acts as a barrier to block harmful gases while allowing wastewater to flow through. P-traps are essential for maintaining indoor air quality and preventing unpleasant odors. They are usually made of materials like PVC, ABS, or metal. Regular maintenance, such as cleaning and checking for clogs, ensures that the P-trap functions effectively and lasts longer.