A "tight seal" refers to a secure closure that prevents the passage of air, liquids, or contaminants between two surfaces. This is often achieved through the use of materials like rubber or silicone gaskets, which compress to fill gaps and create a barrier. Tight seals are essential in various applications, including automobiles, plumbing, and packaging. In the context of containers, a tight seal ensures that contents remain fresh and uncontaminated. For example, jars with screw-on lids or vacuum-sealed bags are designed to maintain a tight seal, prolonging the shelf life of food items. Proper sealing techniques are crucial in industries such as pharmaceuticals and food processing to ensure safety and quality.