|"Is this all real? Or has this been happening inside my head?"
The subject of this article is a real-life person, company, product, or creative work that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really exists), and, as such, details contained in this article may differ from real world facts.
A traffic light is a Muggle device for regulating the flow of vehicular traffic at an intersection, featuring changing signals of light. A green light is used to indicate "go," that vehicles can proceed, while a red light means vehicles must stop in the direction facing that light.
- Harry Potter and the Philosopher's Stone (First mentioned)
- Harry Potter and the Order of the Phoenix (film)