Surface phenomena refer to the behaviors and properties that occur at the interface between different phases, such as solid, liquid, and gas. These phenomena include effects like surface tension, which is the tendency of liquid surfaces to shrink into the minimum surface area possible. This is why small objects, like a needle, can float on water despite being denser than it. Another example of surface phenomena is adsorption, where molecules from a gas or liquid adhere to a solid surface. This process is crucial in various applications, including catalysis and environmental science, as it affects how substances interact at their boundaries, influencing reactions and material properties.