Floo Powder is the substance used in the Harry Potter books (first in "Harry Potter and the Chamber of Secrets")to allow Wizards and Witches to travel from fireplace to fireplace, so long as they are connected to the Floo Network. After the magical powder has been tossed into an appropriate fire, the flames turn emerald green, allowing a person to step into the fire and shout his desired destination. At this point, that person is immediately wisked away, usually ending up in a suitable location. Floo Powder is highly useful because it allows young witches and wizards who cannot yet Disapparate a way to get around long distances, as well as being a cheap and easy form of family transport.