In appearance, dementors are humanoid figures approximately eight feet in height covered in dark, hooded
cloaks which reveal only grey, scabby, decaying hands. They infest the darkest, dankest places and when they breed, they grow
like fungi in these habitats and create an odd fog. The wraith-like creatures have no eyes. They sense and feed on the positive
emotions of human beings, forcing them to relive their worst memories. The very presence of a dementor makes the surrounding
atmosphere grow cold and dark, and the effects are cumulative with the amount of dementors present. Those kept in the company
of a dementor for too long are often driven insane.
The only way to shield oneself from dementors is to use the difficult Patronus Charm to drive
them away. The charm summons a patronus, a sort of physical manifestation of good will, which has no despair for dementors
to thrive on. Chocolate is an effective first aid to mild cases of contact.
In addition to feeding on negative emotions, dementors can perform what is known as the Dementor's
Kiss where the dementor latches its mouth onto a victim's and sucks out the person's soul. The victim is left as an empty
shell, incapable of thought and with no possibility of recovery, though it is only used as punishment for some criminals.