The Langmuir adsorption isotherm is a model that describes how molecules adhere to a solid surface. It assumes that adsorption occurs at specific sites on the surface and that each site can hold only one molecule. This model is useful for understanding how gases or liquids interact with solid materials, particularly in fields like catalysis and environmental science. The isotherm is represented mathematically, showing the relationship between the amount of substance adsorbed and its concentration in the surrounding phase at constant temperature. It helps predict how much of a substance will be adsorbed under various conditions, aiding in the design of adsorption systems and improving efficiency in various applications.