Reference
Definition
What the word means. This is not a work instruction.
Seismic and sway bracing help keep suspended duct and equipment from moving dangerously during seismic or lateral movement. It is controlled by engineered details, spacing, weight, attachment, and local project requirements.
Normal hangers hold weight. Bracing controls movement. Those are related but not the same.
This term belongs to rated, life-safety, grease, or structural work. Knowing the word is fine. Doing the work is a red-lane call — get direction before you touch it.