This document defines equilibrium and describes three types: stable, unstable, and neutral. Equilibrium results when forces acting on a body are balanced, keeping it at rest or in uniform motion. Stable equilibrium restores a body to its original position after displacement, like a book on a table. Unstable equilibrium increases any initial displacement, like a pencil standing on its point. Neutral equilibrium keeps a body's center of gravity in the same position relative to its base during displacement, like rolling a ball. The document also discusses static and dynamic equilibrium.