E-mail Electronic Mail. Messages sent from one computer to another through the Internet.

Error Message A small window window that appears on screen warning the user that a fault has occured and, where appropiate suggesting action to solve the problem.

Expansion Card An add-on piece of hardware that fits into the system untit and expands the function of the PC - for example, a sound card. 

External hardware Additional computer equipment, such as a printer or scanner, attached by able to the system unit.