The fields of application of embedded systems are extremely varied, and differ strongly in complexity.

Embedded processors span the range from simple 4-bit microcontrollers, like those in toys, to powerful 128-bit microprocessors and DSPs.

Some important examples for embedded systems' applications are e.g.:

• Mobile radio
• Traffic control systems
• Automation and control systems
• Medical devices
• Automotive industry
• Aerospace industry
• etc.

The complexity of the applied embedded software varies accordingly.

Some of the embedded systems run a short assembly program from ROM with no operating system.

Many of them run complex multithreaded C/C++ programs under the control of real-time operating systems (RTOS).

Furthermore, it is also increasingly common to find variants of desktop-like operating systems based on Windows and Linux controlling more powerful devices that are still embedded systems (Tablet Computers, Handheld Devices, Smartphones).