What is wrap foil on doorknob when alone?

Wrapping foil around a doorknob when alone is a safety tip that can help prevent unwanted intruders from entering the room. It is recommended to do this when staying in a hotel room or an unfamiliar location alone. By wrapping the foil around the doorknob, any attempt to turn the knob from the outside will create a noticeable noise that will alert you of any attempt to enter the room. While this is not foolproof, it is a simple and effective way to add an extra layer of security and peace of mind when staying alone.