Faraday Cage: An enclosure used to block electromagnetic fields. It is typically formed by a conductive material or a mesh of such material. Named after the English scientist Michael Faraday, who invented them in 1836, Faraday cages work by distributing charge or radiation around the cage’s exterior, thus canceling out electric charges or radiation fields inside the enclosure. Faraday cages are used to protect electronic equipment from lightning strikes and electromagnetic interference (EMI) as well as to prevent EMI from emanating from electronic devices. They are also used in secure environments to prevent eavesdropping or data theft via electronic means.