Poofing is a phrase coined by Edilio (although first used by Quinn who described their history teacher's disappearance in the first few pages of Gone), describing the occurrence of someone reaching the age of fifteen or above and disappearing, tempted out of the FAYZ by the Gaiaphage, which was presumed to devour them and assimilate their intelligence and powers. As a teenager poofs, they see those they love telling them to follow them. If the poofer refuses, their loved-one morphs into something evil and threatens them. Many teens refused this monster and avoided poofing, due to fear over what happens after poofing. Astrid wrote a book, when printers were still available, explaining how to survive the poof but it soon became overlooked.
Some teenagers who "poofed" were later discovered outside of the FAYZ, such as a pair of twins, Emma and Anna, who were unharmed when they poofed. Some later poofers, including Mary Terrafino and Francis, were not so lucky. The poof is also called the Big One-Five and has also been called "stepping out" of the FAYZ.
The only people who deliberately poofed were Francis, Mary and nearly Hunter, but he changed his mind in time.