Apertures in the back panel of the computer allow access to the |expansion cards| from the exterior of the system. This is important as many cards have |ports or connectors| on them for |peripherals cables|. For example, a |network| card fits into one of the expansion slots on the |motherboard|, and has connectors which protrude out of the aperture. A network cable can then be connected to the expansion card without opening the computer. Unused apertures are usually covered by removable metal plates to keep dust out of the system.
