What should be done if someone is unresponsive and not breathing?

When a person is unresponsive and not breathing, the first and most crucial step is to call for emergency help and initiate CPR immediately. This is essential because brain damage can begin within minutes of a lack of oxygen, and timely intervention can significantly increase the chances of survival.

Starting CPR involves providing chest compressions and, if trained, performing rescue breaths. The aim is to circulate any remaining oxygen in the bloodstream and to supply oxygen to the vital organs until professional medical help arrives. Bypassing this step may result in the worsening of the person's condition and could lead to irreversible consequences.

Calling for help promptly ensures that emergency services are en route, which is critical because they can provide advanced care and further interventions that may be necessary once they arrive. Thus, this answer encapsulates the proactive and lifesaving measures required in such a dire situation.