In its most basic form, betel nut is a seed of the Areca catechu, a type of palm tree. It's commonly chewed after being ground up or sliced and wrapped in leaves of the Piper betle vine that have been coated with lime.

Usually for chewing, a few slices of the nut are wrapped in a betel leaf along with calcium hydroxide (slaked lime) and may include clove, cardamom, catechu (kattha), or other spices for extra flavouring.