An O-ring is a circular, doughnut-shaped seal made from flexible materials like rubber or silicone. It is used to prevent the leakage of fluids or gases in various applications, including machinery, plumbing, and automotive systems. The O-ring fits into a groove and creates a tight seal when compressed between two surfaces. O-rings are essential components in many devices, such as engines, pumps, and valves. They come in various sizes and materials to suit different environments and pressures. Proper installation and maintenance of O-rings can significantly enhance the efficiency and longevity of the equipment they are used in.