The recovery position is a first aid technique recommended for assisting people who are unconscious, or nearly so, but are still breathing. It is frequently taught as part of classes in CPR (cardiopulmonary resuscitation}.
It involves turning the unconscious person on their side so that, if stomach contents began to come up, they will reach the mouth and drain out, rather than dropping back into the lungs.
When an unconscious person is lying flat on their back, they are at risk of having stomach contents come up the esophagus and fall back into the lungs.
This is a common risk with unconsciousness caused by excessive alcohol consumption. It is why people die from drinking too much, since alcohol, by itself, is rarely poisonous enough to kill someone on its own. However, if someone passes out, lies flat and then begins to vomit, the vomit often falls back into the lungs rather than exiting the mouth. If the volume of stomach contents is enough, the victim in such a circumstance will actually drown.
It is also a risk with any condition in which a person becomes unconscious.
If the volume is less, the stomach acid will attack the inner lining of the lungs and the victim will suffer a condition known as aspiration pneumonia.
To put someone in the recovery position, first: