Static equilibrium refers to a state where an object remains at rest and experiences no net force or torque acting on it. In this condition, all the forces acting on the object balance each other out, resulting in a stable situation. For example, a book resting on a table is in static equilibrium because the gravitational force pulling it down is balanced by the normal force exerted by the table. In static equilibrium, the sum of all forces and the sum of all torques acting on the object must equal zero. This principle is crucial in various fields, including engineering, architecture, and physics, as it helps ensure structures and systems remain stable and safe under various conditions.