EMI Shielding protects circuits against Electromagnetic interference. This is generally done by encasing the circuit or circuit portion in a conductive container. The containment prevents EMI from passing through. It may be difficult to construct a metal container around a product, so several variations on the "conductive box" theme are available for designers.

One method of EMI Shielding is to apply a very thin (on the order of microns) conductive layer to an item. For example, the unit's plastic case could have thin metallic film applied to its inside. The conductor can vary, but the concept is universal. Another method is to build a small metallic box and use that to surround the portion of the device that requires shielding. Still another method is a hybrid of the two previous ideas - create a plastic shield, but glaze it with a thin layer of conductive metal. These methods can all be applied to a particular component, a board or system, or to the device's enclosure, depending on the needs of the designer.