In contrast to a general-purpose computer such as a personal computer (PC) which is designed to perform a wide range of functions, an embedded system is a specialized computer system designed for one (or a few) specific purpose often with real-time computing constraints. Since the embedded system is dedicated to specific tasks, it can be optimized to smaller size and lower cost while and increasing the reliability and performance.
Typically, an embedded system is housed on a single microprocessor board with the programs stored in ROM. Virtually all appliances that have a digital interface -- watches, microwaves, VCRs, cars may (already) utilize embedded systems. Some embedded systems include an operating system, but many are so specialized that the entire logic can be implemented as a single program.