A computer is a programmable machine that receives input, stores and automatically manipulates data, and provides output in a useful format.
Mechanical examples of computers have existed through much of recorded human history. The first electronic computers were developed in the mid-20th century (1940 - 1945). Originally, they were the size of a large room, consuming as much power as several hundred modern personal computers (PCs).
Modern PCs normally have the following main components:
- A display, known as a monitor. This is the main form of output to the user.
- A keyboard and mouse, the main forms of input by the user.
- Storage drives or disks, where data is stored long term. The following are typical types:
- Optical - CD, DVD and Blu-Ray
- Hard disks
- USB/Thumb/Jump - highly portable storage that plugs directly into the USB port.
- Cards - SD, CompactFlash, and others; typically requires a card reader. Also used in "portable electronics", like MP3 players and digital cameras.
- Power Supply Unit
- Motherboard with CPU
- Graphic system, aka, video card (this is where a GPU might be found).
- Sound system:
- a sound 'card'
- an internal speaker
- external speakers
- Networking devices, such as:
- Network 'card'