Floo powder
Floo powder is a glittery, silver powder used by witches and wizards to travel through the Floo Network. The Network connects most wizarding households and buildings. This powder was invented in the 13th century by Ignatia Wildsmith.
The powder turns a fireplace's flames harmless and emerald green. It is tricky to use; one must toss a handful of powder into a fireplace connected to the Floo Network, walk into the flames, and state the desired destination loudly and clearly to ensure arrival in the proper location. Otherwise, one could end up at the wrong location.
Transportation by floo powder is much quicker than by broomstick, but slower than Apparition. However, unlike Apparition, one does not require a licence to use Floo powder. It can also be used when one places only a part of their body into the flames, to partially transport themselves to another location for direct communication.
From Harry Potter Wiki:Floo Powder
