(1) A combination printer, scanner, copy machine and fax machine. Some all-in-ones exclude the fax capability or make it an option. See
multifunction printer.
(2) A desktop computer that houses every component except the keyboard and mouse inside the same case as the monitor. The all-in-one's primary advantage is saving space on the desk. Its disadvantages are twofold: if any component fails other than the keyboard or mouse, the entire unit must be brought into the shop for repair. Secondly, there is generally no internal expansion for storage; however, external drives can always be added. See
mini PC and
external drive.
An iMac All-In-One
With the computer inside the monitor, iMacs have been very popular since their introduction in 1998. This is a 2009 model (see
iMac).
(Image courtesy of Apple Inc.)