What are low-power modes in microcontrollers?

Low-power modes reduce energy consumption by disabling unused peripherals and reducing clock speeds. Common modes (power decreases, wake capability decreases): Run mode - full operation, all clocks active. Sleep/Idle - CPU stopped, peripherals running, fast wake. Stop/Deep Sleep - most clocks stopped, RAM retained, slower wake. Standby - minimal operation, limited wake sources, RTC may run. Shutdown - lowest power, RAM lost, only specific pins can wake. Power management strategies: Use lowest power mode suitable for wake requirements. Disable unused peripherals. Reduce clock speed when high performance not needed. Use interrupts instead of polling. Optimize wake-up sources (GPIO, timer, UART). Critical for battery-powered IoT devices and wearables.