A desktop computer is a type of computer that fits on or under a desk, usually laying horizontally, compared to a tower that lays vertically. Unlike a laptop, a desktop computer is a stationary computer that remains at a desk. The picture shown is an example set of a desktop computer. Basically, it is composed of CPU casing, mouse, keyboard and monitor. Those were classified as hardware in computer terminology. The operating system or programs that is running or installed on it is called software in computer terminology.
A good option to add in your desktop computer is a UPS or “Uninterrupted Power Supply”. What it does is it will power up your desktop computer for a period of time when you experience power interruption, enough to save your work and shutdown your computer properly. If your budget is not enough, consider buying AVR or “Automatic Voltage regulator” instead to protect your computer from power surge.