What is foil around door knob when home alone?

Foil around the door knob is a safety measure that people can take when they are home alone. It is done to alert the person if someone tries to enter their room or house without their knowledge. The foil makes a noise when the door knob is turned, which can serve as a warning signal that someone is trying to open the door. It is recommended that people also have a backup plan or escape route in case of any emergency. The use of foil around the door knob is a simple and inexpensive way to add an extra layer of security when home alone.