What is real time?

Perhaps more difficult to meet the stereotype "about computer" concept than real time. And yet, as practice shows, not only the majority of users, but most IT professionals have a very vague idea of what lies behind these very common term. Real time - it is actually a sign that the system place a stringent requirement on the reaction rate (response time) to any external events. The term "real time", by the way, almost never used - talk about real-time systems or, more often about real-time. If the system is operating in real time, does not provide the required response time, then talk about her refusal. Real-time systems tend to interact with processes in the real world (hence the "real" time), which usually do not depend on the actions of the system - on the contrary, by the way, the actions of both time and are dependent on external "stimuli". Events in the outside world can occur spontaneously, and the system operates in real time, should alwa...