What is cohesion and adhesion?

Cohesion refers to a liquid's attraction to itself, that is , between its atoms or molecules. Adhesion is the attraction of the liquid to the container holding it. For example, the surface of water in a glass curves upwards at the rim- also known as the meniscus, because adhesion exceeds cohesion. With mercury, the meniscus curves down, because the mercury atoms are more attracted to one another than the glass, and are trying to form a sphere.