A microprocessor (µP) is a multipurpose, programmable, clock-driven, register-based electronic device. It reads binary instructions from memory, accepts binary data as input, processes data according to the instructions, and provides output. It is a complete processing unit with necessary control signals.
- Reads binary instructions from memory.
- Accept binary data as input.
- Process data according to the instructions.
- Provide result as output.

The number of bits a microprocessor recognizes and processes at a time is called a word length. A microprocessor with word length k is referred to as k-bit microprocessor. Intel 8085 is an 8-bit microprocessor because the majority of 8085 instructions are 8 bit.