Permeation is the process by which a substance, such as a gas or liquid, passes through a material. This can occur in various contexts, such as when water seeps through soil or when air moves through a membrane. The rate of permeation depends on factors like the properties of the substance, the material's structure, and environmental conditions. In many applications, understanding permeation is crucial. For example, in the field of materials science, researchers study how different materials, like plastics or metals, resist or allow permeation. This knowledge helps in designing better packaging, protective coatings, and filtration systems.