Much of first aid is common sense, and people are almost certain to learn some elements as they go through their life (such as knowing to apply an adhesive bandage to a small cut on a finger).

However, effective life-saving first aid requires hands-on training by experts, especially where it relates to potentially fatal illnesses and injuries, such as those that require Cardiopulmonary resuscitation (CPR), as the procedures may be invasive, and carry a risk of further injury to the patient - which the ‘3 aims’ of first aid above, clearly try to avoid.

As with any training, it is more useful if it occurs before an actual emergency, although in many countries, emergency ambulance dispatchers will give basic first aid instructions over the phone while the ambulance is on its way.