A microcontroller is a compact integrated circuit designed to perform a specific task in an embedded system. It typically includes a CPU, memory (RAM and ROM), and peripherals (like timers, ADCs, UARTs) all on a single chip. A microprocessor, on the other hand, is just the CPU (central processing unit) and requires external components like RAM, ROM, and I/O interfaces to function. Key Difference: Microcontroller = All-in-one solution for dedicated tasks (e.g., Arduino, STM32). Microprocessor = General-purpose CPU requiring external components (e.g., Intel Core i7, ARM Cortex-A).