Stability is concerned with what happens to a system that is in equilibrium if it is acted upon by a minor disturbance.

If it is stable it returns to its orignal state following removal of the disturbance.

Unstable systems change to a new state following minor disturbance.

Architectural structures must be stable systems.

To achieve stability most architectural structures require to have elements inserted that are not part of the primary load-bearing system.

These are called bracing elements.

Provision of a bracing system is an essential consideration in structural design.