What Is an Embedded System?

Tough question, really. There is no one answer. I asked at least a half dozen industry experts and got as many answers. In fact, it was so hard to pin down a definition that I almost started thinking "embedded system" was just another term for "software." Nevertheless, there's one fact about embedded systems that all the experts do seem to agree on:
An embedded system is any software system that must be designed on a platform different from the platform on which the system is intended to be deployed.
What is meant by platform? On the development side, platform typically refers to an operating system capable of hosting software development, such as Windows, Solaris, HP, etc. On the target side, the word platform refers to the devices on which the embedded system will be deployed.
OK then, why the design constraint? Why aren't embedded targets capable of hosting software development? Because these targets are optimized for performance and/or simplicity, they lack the equipment necessary for development (such as keyboards, monitors, networking, etc.). In general, development for the embedded environment is referred to as "cross-platform development."