O
- open source software
Free software, developed and distributed in the public domain.
- Operating System (OS)
A sequence of programming codes that instructs a computer about its various parts and peripherals and how to operate them. Operating systems, such as Windows Vista, deal only with the workings of the hardware and are separate from software programs.
- OS
See operating system
- OS/2
A graphical operating system designed for use on IBM’s PS/2 line of personal computers. No longer in use.
- Outlook Express
The email client included with previous versions of Windows.
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