The term refers to the latchkey of a door to a house, or home. The key is often strung around the child's neck or left hidden under a mat (or some other object) at the rear door to the property. The term seems to first appear in a CBC radio program called "Discussion Club – Topic: How War Affects Canadian Children" in 1942, due to the phenomenon of children being left home alone during World War II, when the father would be enlisted into the armed forces and the mother would need to get a job. Given that the "Discussion Club" participants are all familiar with the term and allude to it being in colloquial usage, it likely predates 1942. In general, the term latchkey designates "those children between the ages of five and thirteen who care for themselves after the school day until their parents or guardians return home".