Security and Privacy in a Networked World/Operating systems

NOTE: This and a couple of the following, more technical topics make use of Wikipedia articles to provide the basic understanding of the matters (e.g. operating systems in this topic. These articles deal with technology and are not much disputed, having reached the common knowledge stage. They also provide some good links for further study under the reference sections.

What is it?
A computer without any software is only good as a decoration. Software is needed for word processing, web surfing, graphics and many other things. Yet, another thing is needed - the 'middleman' between these programs and the computer that also controls different components of the computer. The middleman is known as the operating system (OS in short).

So the OS has two main roles
 * mediator between the computer and the user. If we had to issue commands directly to the computer, we should use electric signals and binary code. Today's operating systems have come a long way - the early ones had to be controlled by a sophisticated command system, most modern ones sport a graphical user interface (GUI), recent systems also support touch-activated displays.
 * controller of different devices. Clicking the Print button of our web browser sends the command to the OS which in turn instructs the printer what and how should be printed. Likewise, the OS controls scanning the images and displaying them on screen via the graphics editor, sending e-mail through the network interface, playing music via the sound card and speakers, and so on.

READ ON: http://en.wikipedia.org/wiki/Operating_system

Some notes:
 * In earlier days, developing an OS was major task suitable for a close-knit group of specialists (like a company or a research group at an university). Today, the ubiquity of Internet has made it possible to create new OS-es in a variety of ways, there are systems that are run by companies (e.g. Microsoft Windows), purely by community (e.g. Debian GNU/Linux), even single persons (e.g. Slackware Linux) or anything in between these.
 * Also, in early days of computing necessary software (including OS) came along with the computer - hardware was incompatible and most programs only ran on specific computers. With the advent of the PC-compatible class of computers (which means 'the' personal computer for many ordinary users, mass production of software took over. This also created a market for software - what was earlier a complementary tool (like a spare tire coming with a new car) became something that could be turned into a product.  Since then, all proprietary systems - even those coming pre-installed on a new computer - have been paid for by the copy. Yet, many people still assume that "Windows came with the computer" - this is not the case, even if the price is hidden.