O-rings are circular seals made from flexible materials, commonly used to prevent leaks in various mechanical systems. They fit into a groove and create a tight seal when compressed between two surfaces, effectively blocking liquids and gases from escaping. O-rings are widely used in industries such as automotive, aerospace, and plumbing. These seals come in various sizes and materials, including rubber and silicone, to suit different applications and environmental conditions. Proper selection and installation of O-rings are crucial for ensuring their effectiveness and longevity, as improper use can lead to failures and costly repairs.