Faraday cages shield their contents from Electric fields. How does this work? Charge is distributed on the exterior of the cage, so that the Faraday cage acts as a hollow conductor. Therefore, since charge is only around the outside, the net charge inside the cage is zero; and, the E-field is zero inside the Faraday cage.
But, what use is a Faraday cage? Well, this video excerpt from National Geographic's television show "Doomsday Preppers" will give you a whole new perspective on the value of Faraday cages and their potential value for the end of the world. When the end of the world does come, do you want your beloved electronics to be spared from electromagnetic radiation? If you are concerned, stop by the local thrift store like this woman and invest in a Faraday cage.