An S-Trap is a plumbing fixture designed to prevent sewer gases from entering a building. It consists of a curved pipe that resembles the letter "S," which holds a small amount of water. This water acts as a barrier, blocking harmful gases while allowing wastewater to flow through. S-Traps are commonly used in toilets and sinks. However, they can sometimes lead to drainage issues if not installed correctly, as the water seal can be disrupted. Proper installation and maintenance are essential to ensure that the S-Trap functions effectively and safely in any plumbing system.