Shide is a piece of paper used to attach shimenawa, tamagushi, purification sticks, and gohei (sacred staff). The shape of a shide is a representation of lightning.

 Shide are basically attached to tools for purification, but when attached to shimenawa, they represent the domain of the gods. Incidentally, in sumo, yokozuna (grand champion) is wrapped with a shimenawa because he is considered to be close to the gods.