Activated charcoal (also known as "activated carbon") is carbon that has been treated so it becomes incredibly porous, increasing its surface area immensely.[1] It has a variety of uses, including air and water purification, but this seems to be a reference to its use as a medical treatment for poisonings or overdoses due to oral consumption of a foreign substance. Activated charcoal, when ingested, binds to chemicals and prevents their absorption in the gastrointestinal tract.[2]
from Chillout Tent