Adhesion is the process by which different substances stick together. This occurs when molecules from one material interact with molecules from another, creating a bond. For example, when water droplets cling to a leaf, the attraction between the water molecules and the leaf's surface demonstrates adhesion. In everyday life, adhesion is important in various applications, such as in glue and tape, which rely on adhesive properties to hold objects together. Additionally, adhesion plays a crucial role in biological systems, like how cells adhere to each other to form tissues, ensuring proper function and structure.