All-In-One (1) A combination printer, scanner, copy machine and fax machine. Some all-in-ones exclude the fax capability or make it an option. (2) A desktop computer that houses every component except the keyboard and mouse inside the samecase as the monitor. Its primary advantage is saving space.

All-in-one PCs, also known as all-in-one desktops, integrate the computer case and system components into the monitor so that the entire PC  is contained all in one unit.  All-in-one (AIO) desktop PCs offer the advantage of a smaller form factor than desktop PCs, but they often come with several drawbacks as well, including higher cost, weaker performance and limited upgrade options.

The all-in-one computer design debuted with the Apple iMac in 1998.  While the early all-in-one PC computers were expensive and bulky, all-in-one PCs have become much slimmer, lighter and cheaper with the advent of LCD monitors and smaller, less expensive desktop system components.

Some types of AIO PCs have multi-touch display features. The design is user friendly, and accessories and peripherals can be easily connected. Usually located below or on the side of the monitor, the ports are provided at convenient positions for users. One of the primary advantages of using an AIO PC is that it saves space as the monitor is also integrated into the system. The technology used is similar to that used for manufacturing laptops. This also indirectly brings in another benefit, which is the reduction of cables and, hence, of clutter. An AIO PC does not require a separate video cable or a power cord for the monitor. It is also easier to relocate and is much easier to handle in comparison to a desktop computer. Again, compared to a desktop computer, an AIO PC looks more sleek, consumes less power and generates less heat, and is thus more environmentally friendly.

There are, however, certain disadvantages in using an AIO PC. One of the biggest disadvantages is upgradability. The upgradability is generally limited to RAM upgrades. Customizing, tweaking or self-repairing an AIO PC can be rather difficult. The failure of a single component often results in the need to repair/replace the entire unit. Compared to a desktop computer, an AIO PC has lower graphics capabilities and processing speed. It is also much more expensive than a desktop computer.

The manufacturers of the all in one are Hp, Dell, Acer, Lenovo, Samsung, Nvidia, Microsoft etc.