What is the difference between polling and interrupt-driven I/O?

Polling continuously checks peripheral status in a loop, wasting CPU cycles while waiting and potentially missing fast events. Interrupt-driven I/O allows the CPU to perform other tasks until the peripheral signals completion via interrupt. Interrupts are more efficient (no wasted cycles), responsive (immediate notification), and power-efficient (CPU can sleep). Polling is simpler to implement and avoids interrupt overhead. Choice depends on timing requirements, system complexity, and power constraints.