Charcoal is a material we get after burning of trees, it is used in many ways, cooking, drawing sigils, circles, painting and drawing for magical purposes.
Charcoal perform serious wonders if some piece is wrapped in paper (tissue, etc) and placed in ones pocket. This protect you from the evil eye, curses, negative spirits, psychic attacks.
Place 3 pieces of charcoal under your bed while sleeping and you will be protected from the evil eye, curses, negative spirits, psychic attacks.
This is because burning wood on certain days, (such as Yule, Samhain, Beltane, full moons, etc.) Or certain woods will draw that energy into the charcoal and bring certain properties energy to spells and rituals in your craft.