The term 'micro' means extremely small and 'processor' means the thing that accelerates tasks. So in general sense the term 'microprocessor' means an extremely small thing that can accelerate different tasks as ordered. But the actual definition of microprocessor is slightly different than this. A microprocessor is a tiny electronic chip containing transistors found inside a computer's central processing unit and other electronic devices. Its basic function is to take input, process it and then provide appropriate output.
The most important technological invention of recent times is the microprocessor. The developments in the technology of the integrated circuits made it possible for the engineers of the "Intel" corporation of America to develop a micro-programmable computer on a chip in 1971. This device ("Intel 4004") consist of about 2300 transistors on a chip which was fabricated using silicon-gate P-channel MOS technology. It was later named as microprocessor. In figure-a, we have shown a sample of a microprocessor ("Intel 4004). It was a 4-bit microprocessor.